Prior to this commit, the subtype suffix of a MIME type (see RFC 6839)
was not properly taken into account when checking compatibility between
MIME types.
For example, `"application/*"` was not considered as compatible with
`"application/vnd.io.spring+json"`.
This commit adds a new `MimeType#getSubtypeSuffix()` method to easily
extract the subtype suffix information. This method is then reused in
the `isCompatibleWith` implementation to better handle these cases.
Fixes gh-25350
f7a014d7dc