[bazel] Replace gentbl with gentbl_cc_library (llvm#124996)

LLVM has two tablegen generators: one in llvm/tblgen.bzl (`gentbl`,
macro-based) and one in mlir/tblgen.bzl (`gentbl_cc_library`,
rule-based). The `gentbl_cc_library` generator in MLIR has some
advantages to being a rule, and at any rate, it seems better to just use
the same tablegen rule everywhere instead of competing implementations.

Author: rupprecht