Fix bundling and inlining of referenced schemas

[bterlson]

Fixes #3369 by changing how types are bundled. In particular, when a type is not a JSON Schema type, we never create a root schema for it. Instead, it is inlined into the defs of any schema which references it, and referenced using a JSON pointer. This PR makes bundling have essentially no impact on emitted schemas, and is merely a way to bundle them into a single file.

The approach is as follows:

• When a type references another type outside a JSON Schema namespace, include the referenced type under $defs:
  • Such referenced types do not have a $id or $schema field
  • Such referenced types are referenced via JSON pointers not ids
• Bundling does not alter the bundled schemas or introduce new root schemas. This changes two things from what we do today:
  • The $id of the bundled schemas now includes the file path as it does for non-bundled schemas (whereas before it was just the type name)
  • non-JSON Schema types do not get $defs in the bundle, so the bundle has the same root schemas as would be written to disk when not bundling.
     
    In terms of implementation, the basic approach is to not handle bundling via the emitter framework source files. Instead, we always create source files for root schemas, and inline the necessary defs as we did before (but now using JSON pointers). Then when we're about to write source files, if we're bundling we assemble the bundle and emit that single file, otherwise we emit each source file that contains a root schema.

Todo:

• Validate that the bundled schemas continue to work with ajv.
• Cleanups

[azure-sdk]

All changed packages have been documented.

• ✅ @typespec/json-schema

Show changes

@typespec/json-schema - fix ✏️

The emitted JSON Schema now doesn't make root schemas for TypeSpec types which do not have the @jsonschema decorator or are contained in a namespace with that decorator. Instead, such schemas are put into the $defs of any root schema which references them, and are referenced using JSON Pointers.

[azure-sdk]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/prs/3430/

Check the website changes at https://tspwebsitepr.z22.web.core.windows.net/prs/3430/

[bterlson]

@Veetaha if you like you can check the behavior in the playground link above and see if it meets your approval.