feat: add declaration maps for consumers

- fancy source maps for declarations

- apparently I left these out of `ts-library-base` so they didn't get
  copied here either
  - but most of my tsconfig there was copied too, so I suspect I left
    it out either because of @wessberg/rollup-plugin-ts's bugs with it
    or because TSDX previously had bugs with it
    - c.f. ezolenko/rollup-plugin-typescript2#221
      and the worse downstream version I had written first:
      jaredpalmer/tsdx#488

- Unfortunately I did encounter a small error with declaration maps when
  using rpts2 as a configPlugin, due to an unexpected edge case in code
  I wrote myself in the above PR
  - wrote up an issue for it and will probably PR it myself too:
    ezolenko/rollup-plugin-typescript2#310
  - as a workaround, I wrote a small `tsconfig.rollup.json` to be used
    with rpts2 as a configPlugin that disables `declarationMap`
    - and also adds some optimizations over my base tsconfig
    - took me a bit to figure out how to use options with configPlugins,
      as that was one of the reasons I didn't use @rollup/plugin-babel
      as the configPlugin
      - I still can't get it to read my `babel.config.js` even with
        options as it has no option for this (it auto-detects it) :/

package.json

@@ -49,7 +49,7 @@
     "clean": "rm -rf dist/ && rm -f *.tgz",
     "clean:build": "npm run clean && npm run build",
     "build": "concurrently -n rollup,tsc \"npm run build:rollup\" \"npm run build:types\"",
-    "build:rollup": "rollup -c rollup.config.ts --configPlugin rollup-plugin-typescript2",
+    "build:rollup": "rollup -c rollup.config.ts --configPlugin \"rollup-plugin-typescript2={ tsconfig: 'tsconfig.rollup.json' } \" ",
     "build:types": "tsc -p tsconfig.build.json",
     "build:watch": "concurrently -n rollup,tsc \"npm run build:rollup -- -w\" \"npm run build:types -- -w\"",
     "tsc": "tsc",

tsconfig.json

@@ -9,6 +9,8 @@
     "outDir": "dist/",
     // output .d.ts declaration files for consumers
     "declaration": true,
+    // output .d.ts.map declaration map files for consumers
+    "declarationMap": true,
     // output .js.map sourcemap files for consumers
     "sourceMap": true,
     // use Node's module resolution algorithm, instead of the legacy TS one

tsconfig.rollup.json

@@ -0,0 +1,12 @@
+{
+  // tsconfig.json is used for type-checking _all_ files, tsconfig.rollup.json is just used for parsing rollup.config.ts
+  "extends": "./tsconfig.json",
+  // allowlist of files to build -- this is just an optimization
+  "files": ["rollup.config.ts"],
+  "compilerOptions": {
+    // this is currently erroring when used for configPlugins: https://github.com/ezolenko/rollup-plugin-typescript2/issues/310
+    "declarationMap": false,
+  },
+  // read this file as a tsconfig even though it's named slightly differently
+  "$schema": "https://json.schemastore.org/tsconfig",
+}