chore(rc): Move manual typings remote-config typings to separate folder

[MathBunny]

Context

As part of the initiative to auto-generate typings, it would be easier to verify that they are correctly generated if the remote-config manually curated typings were in another file. As part of the gulpfile build process, we could simply ignore the d.ts file.

Solution

Moved the contents to a separate file, following the practice used by many of the other services today.

Test Plan

1. Ran unit, integration and sanity tests.
2. Manually generated the docs, performed quick manual inspection, links work locally (excluding the index).

[lahirumaramba]

Thank you! LGTM!

[lahirumaramba]

Adding release:stage label to run integration tests.

[MathBunny]

Thank you!