size reduction: deduplicate error mappings

[baywet]

We have an opportunity to reduce the size of the projected SDKs, especially in the context of Microsoft Graph.
For a lot of APIs, the schema for the error responses, is the same across the error codes:

• Microsoft Graph describes ODataError for both 4XX and 5XX
• A lot of APIs use the default mapping for errors

Right now we project both those cases to two entries (4XX and 5XX), while it works it's wasteful.

• In the case of default, we could map things to a single XXX entry,
• In the case where we have only 4XX and 5XX, and both codes map to the same schema, we could reduce that to a single XXX entry.

This will require updating the request adapter implementations first to account for that special status code across languages.