[lldb] Skip tests incompatible with older versions of Clang

The coroutine tests require a standard library implementation of
coroutines, which was only made available some time _after_ Clang 13.
The first such Clang tested by the LLDB matrix bot is 15.0.1

The TestObjCExceptions test forces the use of the system's libcxx. For
the lldb matrix bot, the first Clang version compatible with the bot's
libraries is 13.0.

Differential Revision: https://reviews.llvm.org/D134645