Integrate genType docs into main docs as "TypeScript interop"

[fhammerschmidt]

genType has moved into the compiler since 10.1 and flow support has been dropped

Let's move its docs into the main section as "TypeScript interop". Remove all mentions of "flowtype" and "Reason" and update the docs.

[cometkim]

IMHO TypeScript interop shouldn't be treated as special. Except for gentype-specific config, most of it is required for general JS codebase interoperability. Instead, we can say that TypeScript is supported natively.

Instead of the "TypeScript interop" chapter, I suggest providing more generally useful guides in a "Working with JavaScript/TypeScript projects" chapter.

For example, https://rescript-collection.pages.dev/docs/javascript#pipe-operator describes how dealing with pipe patterns in JS codebase.

[fhammerschmidt]

Moving those issues over from #697

• GenType: Add moduleResolution option to customize extensions on emitted import statements. This helps to adjust output compatibility with TypeScript projects using ESM. Add gentypeconfig.moduleResolution options: node16 and bundler for better interop with TS+ESM projects rescript#6182
  • node (default): Drop extensions.
  • node16: Use TS output's extensions. Make it ESM-compatible.
  • bundler: Use TS input's extensions. Make it ESM-compatible.
• GenType: add the option to use the @genType annotation at the module level, meaning that all the items in the module should be exported. Fix @genType issue with module aliases rescript#6113
• GenType: add support for @genType annotations on module definitions. Fix @genType issue with module aliases rescript#6113
• GenType: removed support for @genType.as for records and variants which has become unnecessary. Use the language's @as instead to channge the runtime representation without requiring any runtime conversion during FFI. GenType: removed support for @genType.as in type definitions, which has become unnecessary. rescript#6099 GenType: handle @as(_) in variant declarations. rescript#6101