Implements PheroUnchecked

[kamilafsar]

With the PheroUnchecked utility type, a user can tag a context member to denote that Phero should skip validation for input/output of the middleware/function.

Last 2 commits are random improvements to the codebase

[nloomans]

Nice work! Looking forward to use PheroUnchecked

[nloomans]

Small issue with the documentation, but otherwise LGTM

[nloomans]

"so that Phero will skip it during the parsing step" sounds like Phero will just omit the type. I also don't think users will understand what the "parsing step" refers to.

The example also has issues. JSDoc isn't markdown, so the ```typescript prefix should be omitted. Also the example shows incorrect usage, since we are providing DBClient but asking for RealDB.

How about this?

/**
 * PheroUnchecked<T> is a special type that tells Phero it should not check at
 * runtime if the types actually match what we expect. It may only be used
 * within {@link PheroContext}, and must be provided by a middleware. This is
 * useful for putting types in {@link PheroContext} that would normally be
 * unsupported, such as a classes.
 *
 * @example
 * async function getArticle(ctx: PheroContext<{ db: PheroUnchecked<DBClient> }>): Promise<string> {
 *   return ctx.db.query()
 * }
 *
 * async function myMiddleware(context: PheroContext, next: PheroNextFunction<{ db: PheroUnchecked<DBClient> }>) {
 *   await next({ db: new DBClient() })
 * }
 */

[kamilafsar]

remove the "at runtime" in case Phero will not complain if this does compile:

*   async function getArticle(ctx: PheroContext<{ db: PheroUnchecked<RealDB> }>): Promise<string> {
 *     return ctx.db.query()
 *   }
 *
 *   async function myMiddleware(context: PheroContext, next: PheroNextFunction<{ db: PheroUnchecked<DBClient> }>) {
 *     await next({ db: new DBClient() })
 *   }

Notice the RealDB/DBClient typo