[libc][bazel] Add missing targets for math functions/tests to bazel files

The main aim of this is to add all the targets for math functions which were missed to be added to bazel files.

The issues below can be collaboratively worked on too if needed

- BFloat16: https://github.com/llvm/llvm-project/issues/221026
- Float16: https://github.com/llvm/llvm-project/issues/221799
- Float: https://github.com/llvm/llvm-project/issues/223664
- Double: https://github.com/llvm/llvm-project/issues/223714
- Long double: https://github.com/llvm/llvm-project/issues/223717

(Note: This one's a metaissue/tracking issue only. The linked sub-issues are open to work on. )

Start with the linked BFloat16, Float16, Float, Double, and Long double sub-issues, then inspect the libc Bazel files they identify. Done means the missing math-function and test targets covered by the selected sub-issue are added and the relevant Bazel checks pass.

Written by the indexing model from the issue text.