[LLDB][LoongArch] Add FP branch instructions for EmulateInstructionLoongArch

[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