[CMake][MLIR][Linalg] Adding variable to specify tablegen file dependencies.

Synchronizing multiple custom targets requires not only target but also
file dependencies. Building Linalg involves running yaml-gen followed by
tablegen. Currently, these custom targets are only synchronized using a
target dependency resulting in issues in specific incremental build
setups (https://llvm.discourse.group/t/missing-build-cmake-tblgen-dependency/3727/10).

This patch introduces a novel LLVM_TARGET_DEPENDS variable to the
TableGen.cmake file to provide a way to specify file dependencies.
Additionally, it adapts the Linalg CMakeLists.txt to introduce the
necessary file dependency between yaml-gen and tablegen.

Differential Revision: https://reviews.llvm.org/D105272