[libc][math][c++23] Add f{max,min}imum{,_mag,_mag_num,_num}bf16 math functions (#152881)
This PR adds the following basic math functions for BFloat16 type along
with the tests:
- fmaximumbf16
- fmaximum_magbf16
- fmaximum_mag_numbf16
- fmaximum_numbf16
- fminimumbf16
- fminimum_magbf16
- fminimum_mag_numbf16
- fminimum_numbf16
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Signed-off-by: Krishna Pandey <kpandey81930@gmail.com>