Decode Ada types in Python layer

Decode Ada types in Python layer

GNAT emits encoded type names, but these aren't usually of interest to
users.  The Ada language code in gdb hides this oddity -- but the
Python layer does not.  This patch changes the Python code to use the
decoded Ada type name, when appropriate.

I looked at decoding Ada type names during construction, as that would
be cleaner.  However, the Ada support in gdb relies on the encodings
at various points, so this isn't really doable right now.

2021-06-25  Tom Tromey  <tromey@adacore.com>

	* python/py-type.c (typy_get_name): Decode an Ada type name.

gdb/testsuite/ChangeLog
2021-06-25  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/py_range.exp: Add type name test cases.