[API] Add MemoryExtensions.Contains #25228
Description
Proposal:
public static class MemoryExtensions {
bool Contains<T>(this Span<T> span, T value);
bool Contains<T>(this ReadOnlySpan<T> span, T value);
bool Contains<T>(this Span<T> span, T value, IEqualityComparer<T> comparer);
bool Contains<T>(this ReadOnlySpan<T> span, T value, IEqualityComparer<T> comparer);
}This is different from the IndexOf method in that we can perform certain optimizations if we know you don't need the exact index of where the value was found. There are a few places in the framework that would benefit from this.