Add api-extractor generated docs for di and context export paths (#6979)

# Pull Request

## 📖 Description

This change points the `api-extractor` to the `di` and `context` export paths and adds this generated documentation to the documentation site.

### 🎫 Issues

Resolves #6090

## 👩‍💻 Reviewer Notes

This is was a little fiddly as the `api-extractor` does not export export paths, additionally the way the `api-documentor` works assumes a single entry path. This is why if any additions need to be made to expose more export paths, we will need to edit 3 different files to get the documentation to show up on the documentation website.

## ✅ Checklist

### General

<!--- Review the list and put an x in the boxes that apply. -->

- [x] I have included a change request file using `$ yarn change`
- [ ] I have added tests for my changes.
- [x] I have tested my changes.
- [x] I have updated the project documentation to reflect my changes.
- [x] I have read the [CONTRIBUTING](https://github.com/microsoft/fast/blob/master/CONTRIBUTING.md) documentation and followed the [standards](https://github.com/microsoft/fast/blob/master/CODE_OF_CONDUCT.md#our-standards) for this project.

change/@microsoft-fast-element-d3208e54-7afa-44a5-9763-acecac743653.json

@@ -0,0 +1,7 @@
+{
+  "type": "none",
+  "comment": "Add api-extractor generated docs for di and context export paths",
+  "packageName": "@microsoft/fast-element",
+  "email": "7559015+janechu@users.noreply.github.com",
+  "dependentChangeType": "none"
+}

packages/web-components/fast-element/api-extractor.context.json

@@ -0,0 +1,14 @@
+{
+    "$schema": "https://developer.microsoft.com/json-schemas/api-extractor/v7/api-extractor.schema.json",
+    "extends": "../../../api-extractor.json",
+    "mainEntryPointFilePath": "./dist/dts/context.d.ts",
+    "apiReport": {
+        "enabled": true,
+        "reportFolder": "<projectFolder>/docs/context",
+        "reportFileName": "api-report.md"
+    },
+    "docModel": {
+        "enabled": true,
+        "apiJsonFilePath": "<projectFolder>/dist/context/context.api.json"
+    }
+  }

packages/web-components/fast-element/api-extractor.di.json

@@ -0,0 +1,14 @@
+{
+    "$schema": "https://developer.microsoft.com/json-schemas/api-extractor/v7/api-extractor.schema.json",
+    "extends": "../../../api-extractor.json",
+    "mainEntryPointFilePath": "./dist/dts/di/di.d.ts",
+    "apiReport": {
+        "enabled": true,
+        "reportFolder": "<projectFolder>/docs/di",
+        "reportFileName": "api-report.md"
+    },
+    "docModel": {
+        "enabled": true,
+        "apiJsonFilePath": "<projectFolder>/dist/di/di.api.json"
+    }
+  }

packages/web-components/fast-element/docs/context/api-report.md

@@ -0,0 +1,69 @@
+## API Report File for "@microsoft/fast-element"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+
+// @public
+export type Context<T> = {
+    readonly name: string;
+    readonly initialValue?: T;
+};
+
+// @public
+export const Context: Readonly<{
+    eventType: "context-request";
+    for<T = unknown>(name: string): FASTContext<T>;
+    create<T_1 = unknown>(name: string, initialValue?: T_1 | undefined): FASTContext<T_1>;
+    setDefaultRequestStrategy(strategy: FASTContextRequestStrategy): void;
+    get<T_2 extends UnknownContext>(target: EventTarget, context: T_2): ContextType<T_2>;
+    request<T_3 extends UnknownContext>(target: EventTarget, context: T_3, callback: ContextCallback<ContextType<T_3>>, multiple?: boolean): void;
+    dispatch<T_4 extends UnknownContext>(target: EventTarget, context: T_4, callback: ContextCallback<ContextType<T_4>>, multiple?: boolean): void;
+    provide<T_5 extends UnknownContext>(target: EventTarget, context: T_5, value: ContextType<T_5>): void;
+    handle<T_6 extends UnknownContext>(target: EventTarget, callback: (event: ContextEvent<T_6>) => void, context?: T_6 | undefined): void;
+    defineProperty<T_7 extends UnknownContext>(target: Constructable<EventTarget> | EventTarget, propertyName: string, context: T_7): void;
+}>;
+
+// @public
+export type ContextCallback<ValueType> = (value: ValueType, dispose?: () => void) => void;
+
+// Warning: (ae-forgotten-export) The symbol "ParameterDecorator" needs to be exported by the entry point context.d.ts
+//
+// @public
+export type ContextDecorator<T = any> = Readonly<Context<T>> & PropertyDecorator & ParameterDecorator_2;
+
+// @public
+export class ContextEvent<T extends UnknownContext> extends Event {
+    constructor(context: T, callback: ContextCallback<ContextType<T>>, multiple?: boolean | undefined);
+    // (undocumented)
+    readonly callback: ContextCallback<ContextType<T>>;
+    // (undocumented)
+    readonly context: T;
+    // (undocumented)
+    readonly multiple?: boolean | undefined;
+}
+
+// @public
+export type ContextType<T extends UnknownContext> = T extends Context<infer Y> ? Y : never;
+
+// @public
+export type FASTContext<T> = ContextDecorator<T> & {
+    get(target: EventTarget): T;
+    provide(target: EventTarget, value: T): void;
+    request(target: EventTarget, callback: ContextCallback<T>, multiple?: boolean): void;
+    handle(target: EventTarget, callback: (event: ContextEvent<FASTContext<T>>) => void): void;
+};
+
+// @public
+export type FASTContextRequestStrategy = <T extends UnknownContext>(target: EventTarget, context: T, callback: ContextCallback<ContextType<T>>, multiple: any) => void;
+
+// @public
+export type UnknownContext = Context<unknown>;
+
+// Warnings were encountered during analysis:
+//
+// dist/dts/context.d.ts:127:5 - (ae-forgotten-export) The symbol "Constructable" needs to be exported by the entry point context.d.ts
+
+// (No @packageDocumentation comment for this package)
+
+```