Port stdlib functions to new backend

[pbiggar]

The major effort at the moment is to rewrite the backend (currently in OCaml) to F#. A large part of that it to port all the stdlib functions.

It's easy to see which functions need to be ported as they are commented out (here and here).

There is a guide to port stdlib functions here.

This is the latest list of functions that needs to be ported:
Not yet implemented: HttpClient::delete
Not yet implemented: HttpClient::delete_v1
Not yet implemented: HttpClient::delete_v2
Not yet implemented: HttpClient::delete_v3
Not yet implemented: HttpClient::delete_v4
Not yet implemented: HttpClient::get
Not yet implemented: HttpClient::get_v1
Not yet implemented: HttpClient::get_v2
Not yet implemented: HttpClient::get_v3
Not yet implemented: HttpClient::get_v4
Not yet implemented: HttpClient::head
Not yet implemented: HttpClient::head_v1
Not yet implemented: HttpClient::head_v2
Not yet implemented: HttpClient::head_v3
Not yet implemented: HttpClient::head_v4
Not yet implemented: HttpClient::options
Not yet implemented: HttpClient::options_v1
Not yet implemented: HttpClient::options_v2
Not yet implemented: HttpClient::options_v3
Not yet implemented: HttpClient::options_v4
Not yet implemented: HttpClient::patch
Not yet implemented: HttpClient::patch_v1
Not yet implemented: HttpClient::patch_v2
Not yet implemented: HttpClient::patch_v3
Not yet implemented: HttpClient::patch_v4
Not yet implemented: HttpClient::post
Not yet implemented: HttpClient::post_v1
Not yet implemented: HttpClient::post_v2
Not yet implemented: HttpClient::post_v3
Not yet implemented: HttpClient::post_v4
Not yet implemented: HttpClient::put
Not yet implemented: HttpClient::put_v1
Not yet implemented: HttpClient::put_v2
Not yet implemented: HttpClient::put_v3
Not yet implemented: HttpClient::put_v4
Not yet implemented: StaticAssets::baseUrlFor
Not yet implemented: StaticAssets::baseUrlForLatest
Not yet implemented: StaticAssets::fetch
Not yet implemented: StaticAssets::fetchBytes
Not yet implemented: StaticAssets::fetchLatest
Not yet implemented: StaticAssets::fetchLatestBytes
Not yet implemented: StaticAssets::fetchLatest_v1
Not yet implemented: StaticAssets::fetch_v1
Not yet implemented: StaticAssets::serve
Not yet implemented: StaticAssets::serveLatest
Not yet implemented: StaticAssets::serveLatest_v1
Not yet implemented: StaticAssets::serve_v1
Not yet implemented: StaticAssets::urlFor
Not yet implemented: StaticAssets::urlForLatest
Not yet implemented: Twilio::sendText
Not yet implemented: Twilio::sendText_v1

[pbiggar]

HttpClient functions being worked on in #3256. All other functions rely on those so this is blocked for now.

[pbiggar]

When #3510 merges, all functions will be implemented.

LibStaticAssets and LibTwilio will still need to be tested, probably in production.

[pbiggar]

Merged, there are still some untested functions, but we can do that in another issue.