[PatternRewriter] Rename OwningRewritePatternList -> RewritePatternSet and insert -> add

This maintains the old name to have minimal source impact on downstream codes, and
does not do the huge mechanical patch.  I expect the huge mechanical patch to land
sometime this week, but we can keep around the old names for a couple weeks to reduce
impact on downstream projects.

Differential Revision: https://reviews.llvm.org/D99119