[mlir][IR] Use tablegen for the BuiltinDialect and operations

This has been a long standing TODO, and cleans up a bit of IR/. This will also make it easier to move FuncOp out of IR/ at some point in the future. For now, Module.h and Function.h just forward BuiltinDialect.h. These files will be removed in a followup.

Differential Revision: https://reviews.llvm.org/D91571