oe-selftest: devtool ide-sdk: add test for ide=none LLDB/clang support

oe-selftest: devtool ide-sdk: add test for ide=none LLDB/clang support

Add test_devtool_ide_sdk_none_cmake_clang to DevtoolIdeSdkTests to
exercise the new LldbServerConfigNone code path in ide_none.py.

The test uses the cmake-example-clang recipe (TOOLCHAIN = "clang") and
runs devtool ide-sdk with --ide=none.  It verifies:

- lldb_server_<port>_<binary>_multi script is generated
- lldbinit/lldbinit_<port>_<binary> init file is generated
- lldb_<port>_<binary> wrapper script is generated
- No gdbserver_* script is generated for a clang recipe
- The install_and_deploy script exists
- The oe-scripts symlink inside the source tree is valid
- lldb-server can be started on the target via the generated script
- The pid file written by the start script references the live process
- An lldb --batch session using the generated wrapper reaches main and
  can evaluate CppExample::test_string at the breakpoint
- lldb-server stops cleanly via the generated stop script

A new helper _lldb_none_debugging_multi is added alongside the
existing _gdb_cross_debugging_multi, following the same structure.

Signed-off-by: Adrian Freihofer <adrian.freihofer@siemens.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>