std::assert::assert_matches! module name conflicts with std::assert! macro name

[richkadel]

#86947 recently landed, but in some situations, compiling with code that references both the std::assert macro and the assert_matches macro creates a name collision (at best, confusing error messages when std::assert appears to be feature gated, but there are other more complicated errors that are harder to workaround).

The new assert module name is not important, so changing the name to something else should be OK, and would resolve the name collision.

[richkadel]

Fixed by #87195