Add CI job with clang tidy

[t-b]

This can already be done locally

cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=true ..
clang-tidy $(find ../cppapi -iname "*.cpp")

which gives warnings.zip

and manually filtered

$grep "warning:" warnings.log | grep -oP "\[clang.*\]" | sort | uniq -c
     18 [clang-analyzer-core.CallAndMessage]
     30 [clang-analyzer-core.NonNullParamChecker]
     71 [clang-analyzer-core.NullDereference]
      8 [clang-analyzer-core.UndefinedBinaryOperatorResult]
      4 [clang-analyzer-core.uninitialized.Assign]
     12 [clang-analyzer-core.uninitialized.UndefReturn]
      2 [clang-analyzer-cplusplus.NewDelete]
      2 [clang-analyzer-cplusplus.NewDeleteLeaks]
     26 [clang-analyzer-deadcode.DeadStores]
     22 [clang-analyzer-optin.cplusplus.VirtualCall]
    135 [clang-analyzer-security.insecureAPI.strcpy]
      3 [clang-analyzer-unix.MismatchedDeallocator]
      3 [clang-diagnostic-absolute-value]
      2 [clang-diagnostic-instantiation-after-specialization]
      4 [clang-diagnostic-string-plus-int]

[mliszcz]

This can already be done locally

Still I think it would be useful to consider:

• adding .clang-tidy config file with more checks enabled (especially checks related to code readability) and some other disabled (like maybe the one for non-optimal padding, which generates a lot of noise)
• running multiple tidy instances in parallel with run-clang-tidy.py script or gnu parallel or something else (related: https://reviews.llvm.org/D54141)
• ensure that we don't see duplicates coming from the same header included in multiple TUs
• ensure that warnings coming from third-party libraries are not reported.

For instance I remember seeing NullDereference reported multiple times (probably false positive) in omniORB's stringtypes.h and seqTemplatedecls.h when running clang-tidy on our attribute.cpp. I could not get rid of this neither with -line-filter nor with -header-filter.