[LLDB][LoongArch] Add FP branch instructions for EmulateInstructionLoongArch
Add floating-point branch Instructions for EmulateInstructionLoongArch and
add relevant unit tests.
Without this patch:
```
$ ninja check-lldb-unit
[0/1] Running lldb unit test suite
Testing Time: 10.45s
Passed: 1044
```
With this patch:
```
$ ninja check-lldb-unit
[0/1] Running lldb unit test suite
Testing Time: 10.20s
Passed: 1048
```
Reviewed By: SixWeining, MaskRay, DavidSpickett
Differential Revision: https://reviews.llvm.org/D140759