The latest cppcheck supports reading `compile_commands.json` from the
CMake build directory to get a list of files to check and compiler flags
to use. This is better than simply checking all files recursively
without dedicated flags for each file, which we have been doing before,
because
* when checking all files recursively in one invocation of cppcheck,
cppcheck treats code from all examples as part of one big project and
incorrectly warns of duplicated class definitions from different
examples
* the compiler flags from `compile_commands.json` provide more complete
information to cppcheck such as header include paths (among others), so
that cppcheck can, for example, perform complete analysis of both class
declaration in header and definition in source in one combined context,
catching problems that have been missed before.

Thus, run cppcheck using `compile_commands.json` generated by CMake, in
each build job in CI. Disable the pre-commit hook that checks on all
files recursively in one go.

Notes:
* We suppress a few types of errors:
  - `internalAstError`: cppcheck internal error, which we can't handle
  - `preprocessorErrorDirective`: `#include` failure in glue code, due
  to missing config headers (e.g. `mbedtls_config.h`) and macros when
  the current example (e.g. littlefs) doesn't really need to provide the
  header
  - `unmatchedSuppression`: the two aforementioned suppressions are not
  matched/needed
* CMake has built-in support for cppcheck, which can be enabled via the
variables `CMAKE_{C,CXX}_CPPCHECK`. But if we use it, we would need to
set those variables wherever we add our own code and unset it wherever
we make available fetched third-party code (which likely fails checks).
It is more intrusive and less handy than passing `compile_commands.json`
directly to cppcheck and filtering out files from the build directory.

Signed-off-by: Lingkai Dong <lingkai.dong@arm.com>