[libc][nfc] add CPP Limits.h for numeric_limits

Add an implementation of numeric_limits for use in str_conv_utils.
It currently only supports the basic integer types, with more types
coming as needed.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D107987

GitOrigin-RevId: 472fa04de8f3c0e0381d2209ed01d3c18b4ecf4a
2 files changed