Circular reference fixes

[bterlson]

fix #3447
Fixed a few issues with circular references in the JSON Schema emitter and emitter framework:

• The emitter framework wouldn't restore context correctly when directly emitting a type reference to a type with a circular reference.
• The JSON Schema emitter did not handle circular references involving non-JSON Schema types.
• The JSON Schema emitter would create an infinite loop when circular references needed to be put into $defs.

[azure-sdk]

All changed packages have been documented.

• ✅ @typespec/compiler
• ✅ @typespec/json-schema

Show changes

@typespec/compiler - fix ✏️

Emitter framework: fix losing context when referencing circular types

@typespec/json-schema - internal ✏️

[azure-sdk]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/prs/3451/

Check the website changes at https://tspwebsitepr.z22.web.core.windows.net/prs/3451/