[clang-tidy] Add support for long double in bugprone-incorrect-roundings

Support all floating point representations for an 0.5 floating const.
Added missing tests.

Depend on D147906.

Reviewed By: carlosgalvezp

Differential Revision: https://reviews.llvm.org/D147908

GitOrigin-RevId: aa1642f6cc4ac8403b21f998a1234bea2948ac9d
3 files changed