Improve pref of `Array.IndexOf()` for certain `T`. (dotnet/coreclr#24293)
Improve pref of `Array.IndexOf()` for certain `T`. (dotnet/coreclr#24293)

Applies changes to `Array.IndexOf()` and `Array.LastIndexOf()` similar
to the changes made in #20855, so that types other than `byte` and
`char` can use use the fast vectorized path.

Also allows 32-bit and 64-bit types for which
`RuntimeHelpers.IsBitwiseEquatable<T>()` returns `true` to use the
faster implementation of `IndexOf` and `LastIndexOf` from
`MemoryExtensions`.

Signed-off-by: dotnet-bot <03c4cb6107ae99956a7681f2c97ff7104809a2bd@microsoft.com>

shimingsg/corefx,ericstj/corefx,shimingsg/corefx,wtgodbe/corefx,ViktorHofer/corefx,shimingsg/corefx,BrennanConroy/corefx,shimingsg/corefx,ericstj/corefx,ViktorHofer/corefx,shimingsg/corefx,BrennanConroy/corefx,ViktorHofer/corefx,wtgodbe/corefx,ViktorHofer/corefx,ericstj/corefx,wtgodbe/corefx,ericstj/corefx,wtgodbe/corefx,BrennanConroy/corefx,ericstj/corefx,ericstj/corefx,wtgodbe/corefx,ericstj/corefx,ViktorHofer/corefx,wtgodbe/corefx,shimingsg/corefx,ViktorHofer/corefx,shimingsg/corefx,wtgodbe/corefx,ViktorHofer/corefx