Allow ServletContext level removal of `TRACE` from `OPTIONS` response `Allow` header

Currently, the only way to remove TRACE from the OPTIONS response `Allow` header is to override the `doOptions` method on every servlet you implement.
This isn't always feasible with 3rd party libraries and whatnot.

While there is a way to use Constraint mappings to disable TRACE (well, it actually returns "403 Not Authorized" instead of the more useful "405 Method Not Allowed") at the ServletContext level, there's no way to have that change also impact the OPTIONS `Allow` header at the same time.

Start by reviewing the ServletContext constraint-mapping behavior and the servlet OPTIONS response rules. Determine how disabling TRACE at the context level should affect the Allow header and status response; done when the context-level configuration removes TRACE from Allow without requiring per-servlet doOptions overrides.

Written by the indexing model from the issue text.