[RISCV] Add TuneJumpIsExpensive (#191374)
We had `setJumpIsExpensive(true)` before 18.x but it was removed
in #74647. This feature allows users to tune the ISel behavior.
We have #80124 and #178394 landed, so it should be more flexible
to tune branches and selects now.
This is an alternative of #191158.
