[feature] Support extended json

[1aam2am1]

Hi, I would like to request a extension to json support:

• inline comments

  { // some comment 
  "key": "value" // some comment
  }

• block comments

  { /* Block comment
  Or multiline
  */
  "key": "value"
  }

• enum value not as string

  {
  "key": enum_value,
  "key_second": "other_value"
  }

As for example these jsons are valid for flatbuffer complier
https://flatbuffers.dev/flatbuffers_guide_writing_schema.html#autotoc_md29

And pydantic would be great for batch processing of such JSON configurations.

[davidhewitt]

As per #91 I think comment support is straightforward subject to performance impact.

For the enum values, that's a much more complicated / interesting idea which would have a strong interaction with pydantic-core. I'm open to someone exploring this idea, but it's a much bigger feature request and would have questions all the way up to the pydantic main API (as I assume users would want to be able to configure this).