Better error reporting in Local API when the collection is not found

[jmikrut]

Right now, if you are using the Local API and you have a typo in your collection slug, the operation will fail because the referenced collection will not be found.

Instead of failing with a non-descriptive error message, we should throw an error that describes what happened more clearly.

This affects only the Local API and the local operations should be the only thing needing to be touched here.

For example, in the findByID local operation (/src/collections/operations/local/findByID.ts):

export default async function findByIDLocal<T extends TypeWithID = any>(payload: Payload, options: Options): Promise<T> {
  // ... the operation code here

  const collection = payload.collections[collectionSlug];

  // New code starts here

  if (!collection) {
    throw new APIError(`The collection with slug ${collectionSlug} can't be found.`);
  }

  // End of new code, rest of operation goes here
}

We would want to go through and do this for all local operations.