NFC: Implement OwningRewritePatternList as a class instead of a using directive.

NFC: Implement OwningRewritePatternList as a class instead of a using directive.

This allows for proper forward declaration, as opposed to leaking the internal implementation via a using directive. This also allows for all pattern building to go through 'insert' methods on the OwningRewritePatternList, replacing uses of 'push_back' and 'RewriteListBuilder'.

PiperOrigin-RevId: 261816316