Fuse the RHS constant into corresponding op

[ShangkunLi]

In this pr:

• Provide a template to fuse the RHS constant into its operation
• Separate the optimization pass as HWAgnostic optimization (e.g., fold-constant) and HWSpecific optimization (e.g., fuse-loop-control)
• I have removed some predicate attributes in the NeuraOps.td because we need to enable the $rhs as an optional operand. And multiple optional operands are not allowed in mlir.

After applying the fold-constant, the number of ops can be greatly reduced.

For dataflow branch_for.mlir, 40 lines -> 25 lines.
For dataflow simple_loop.mlir, 53 lines -> 29 lines.