[lldb] Adjusting the base MCP protocol types per the spec. (#153297)

* This adjusts the `Request`/`Response` types to have an `id` that is
either a string or a number.
* Merges 'Error' into 'Response' to have a single response type that
represents both errors and results.
* Adjusts the `Error.data` field to by any JSON value.
* Adds `operator==` support to the base protocol types and simplifies
the tests.

GitOrigin-RevId: 350f6abb8304bae39a0ed70a41fde13b7d1df510
8 files changed