[lldb][AArch64][Linux] Add fields for FPCR register (#71694)

Follows the format laid out in the Arm manual, AArch32 only fields are
ignored.

```
(lldb) register read fpcr
    fpcr = 0x00000000
         = (AHP = 0, DN = 0, FZ = 0, RMMode = 0, FZ16 = 0, IDE = 0, IXE = 0, UFE = 0, OFE = 0, DZE = 0, IOE = 0)
```

Tests use the first 4 fields that we know are always present.

Converted all the HCWAP defines to `UL` because I'm bound to
forget one if I don't do it now.