[mono][jit] More SIMD cleanups (#97958)

* Factor out common code from the arch_emit_simd_intrinsics () functions into a new function.
* Add support for all vector sizes to emit_simd_intrinsics (), disable them later using ifdefs
  in emit_sri_vector ().
* Add support for IsSupported/Count properties for all vector types even if they are not supported
  on a platform.
  This helps with dead code elimination since the bcl contains a lot of checks for these properties.
* Rename some functions to better match their functionality.
* Remove the emit_vector256_t () function, Vector256 is now handled normally by
  emit_sri_vector_t ().