posix: move limit definitions to common libc limits.h

In order to reduce conflicts with limits defined in external C libraries,
move Zephyr's POSIX limits from posix_features.h to limits.h in the
common C library sources.

In order to give the implementation better control over where POSIX
limit definitions originate, use `#include_next <limits.h>` to pull in
the corresponding header of the C library, and provide a non-user
configurable option `CONFIG_TC_PROVIDES_POSIX_LIMIT_DEFS` that may be set
in order to ensure that the C library version of POSIX limits are used.

Note: this may mean that runtime invariant values are inconsistent with
parts that are actually in use within Zephyr, so applications are
encouraged to use `sysconf()` with external C libraries that implement
parts of the POSIX standard to query system configuration values at
runtime.

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>