packaging: replace pkg_resources libclang check

Use importlib.metadata to detect an installed libclang distribution
instead of the deprecated pkg_resources API. pkg_resorces has been
deprecated in setuptools v67.5.0 and removed in v82.0.0.
Bump c-picker to 1.0.2 and document the packaging change in the release
notes.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: I4d8c725d334b95add9cd66baa1e818122ffc164c
3 files changed