[clang-tidy] Add options to describe individual core increments to readability-functi...

[clang-tidy] Add options to describe individual core increments to readability-function-cognitive-complexity check.

Often you are only interested in the overall cognitive complexity of a
function and not every individual increment. Thus the flag
'DescribeBasicIncrements' is added. If it is set to 'true', each increment
is flagged. Otherwise, only the complexity of function with complexity
of at least the threshold are flagged.

By default 'DescribeBasisIncrements' is set to 'true', which is the original behavior of the check.

Added a new test for different flag combinations.

(The option to ignore macros which was original part of this patch will be added in another path)

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D96281