Move most of "ada/*" to the root directory (this makes sense, as this
repository has been dedicated to Libadalang for years), and rename
"ada/language" to "ada".
TN: T914-010
Add a check in high-level parser function to make sure that all tokens
are consumed by the parser. Also add an option to disable this check.
Fix testcases to strip trailing tokens that are no longer not accepted.
Followup on O525-009
Change-Id: I66799941ea8b37b95cf6b7ea25aa62cf04b01e7a