Add support for condition in Ada exception catchpoint commands

Add support for condition in Ada exception catchpoint commands

Previously, conditions could be associated to Ada exception catchpoints,
but not while creating the exception catchpoint:

    (gdb) catch exception first_exception if except_counter = 5
    Junk at end of expression

This patch improves the parsing of the command arguments to allow
an "if CONDITION" at the end.  All Ada exception catchpoint commands
have been enhanced to support this.

gdb/ChangeLog:

        * ada-lang.c (catch_ada_exception_command_split): Add new
        argument cond_string.  Add support for condition at end of
        "catch exception" commands.
        (ada_decode_exception_location): Add new argument cond_string.
        Update call to catch_ada_exception_command_split.
        (create_ada_exception_catchpoint): Add new argument cond_string.
        Set the breakpoint condition if needed.
        (catch_ada_exception_command): Update call to
        ada_decode_exception_location.
        (ada_decode_assert_location): Add function documentation.
        Add support for condition at end of "catch assert" command.
        (catch_assert_command): Update calls to ada_decode_assert_location
        and create_ada_exception_catchpoint.