As mentioned in #1553

The only exception is the "Normal" blend op, which was re-written (and cleaned up) separately as part of #1696

The parts removed were:

• The methods named "CreateWithOpacity " and related classes. In #1696 I floated the following idea:

  ...if we want the blend ops to offer that in the future [...] I think it doesn't need to be implemented separately for every blend op, but it can be implemented once and then composed...

• The Apply method overrides with Span and ReadOnlySpan parameters. As explained in #1696:

  They are almost exactly the same code as the original virtual methods, the only difference being that the overrides call ApplyStatic. I think the JIT compiler can optimize that out and de-virtualize and/or inline these calls.