[ASTMatchers] Fixed CastKind being parsed incorrectly for dynamic matchers

Summary: Requires hasCastKind arguments to have `CK_` prefixed to bring it in line with the documentation and other matchers that take enumerations.

Reviewers: klimek, aaron.ballman

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77503