feat: add support for typed methods

[atkinchris]

This adds support for typed methods, by generating endpoint and method types. This is largely taken from scripts in @octokit/plugin-rest-endpoint-methods.

As @octokit/types does not support GHEC types, we cannot import endpoint types directly. Instead, we generate them for this package from @octokit/openapi-types-ghec.

[github-actions]

👋 Hi! Thank you for this contribution! Just to let you know, our GitHub SDK team does a round of issue and PR reviews twice a week, every Monday and Friday! We have a process in place for prioritizing and responding to your input. Because you are a part of this community please feel free to comment, add to, or pick up any issues/PRs that are labeled with Status: Up for grabs. You & others like you are the reason all of this works! So thank you & happy coding! 🚀

[atkinchris]

Bizarrely, I'm seeing a TS2339 error for some of the Endpoint keys - which looks like a false positive. As an example:

plugin-enterprise-cloud.js/src/generated/parameters-and-response-types.ts

Lines 204 to 208 in ed9bb18

	deleteUserFromEnterprise: {
	parameters: RequestParameters &
	Endpoints["DELETE /scim/v2/enterprises/{enterprise}/users/{scim_user_id}"]["parameters"];
	response: Endpoints["DELETE /scim/v2/enterprises/{enterprise}/users/{scim_user_id}"]["response"];
	};

However, it does exist!

plugin-enterprise-cloud.js/src/generated/endpoints-types.ts

Lines 236 to 242 in ed9bb18

	/**
	* @see https://docs.github.com/enterprise-cloud@latest//rest/enterprise-admin/scim#delete-a-scim-user-from-an-enterprise
	*/
	"DELETE /scim/v2/enterprises/{enterprise}/Users/{scim_user_id}": Operation<
	"/scim/v2/enterprises/{enterprise}/Users/{scim_user_id}",
	"delete"
	>;