Deprecation/removal of obsolete features

[cknitt]

This is an umbrella issue for obsolete features that should be deprecated/removed.

My suggestions would be to have them deprecated in an 11.1.x release and removed in v12.

• JSX 3 (Deprecate/remove JSX v3 #6982)
• OCaml stdlib functions (Deprecate/remove OCaml stdlib functions #5779)
• Js namespace (WIP: Deprecate Js namespace #7510)
• Functions in Belt that are covered by the new stdlib
• bsconfig.json (Drop bsconfig.json support entirely #6781)
• -bs-g bsc-flag (Deprecate -bs-g bsc-flag #6496)
• js_cast.ml (Deprecate js_cast.ml? #5439)

[cometkim]

#6781 is waiting for v12.x release

[fhammerschmidt]

what about #7056 ?

[zth]

Deprecation of the Js namespace could be worked on in tandem with this PR for adding automigrations: #7693