[LLDB][RISCV] Add RV32F instruction support for EmulateInstructionRISCV

Add:

- RV32F instruction set.
- corresponding unittests.

Further work:

- RV32FC, RV64F and RV64FC instructions support.
- update execution exceptions to fcsr register in RVM instructions.

Reviewed By: DavidSpickett

Differential Revision: https://reviews.llvm.org/D138447