Add ability to debug additional registers via gdb

[jsturtevant]

This pull request adds support for reading and writing XMM and MXCSR registers in the GDB debug interface for all supported hypervisors (KVM, MSHV, and WHVP). It introduces new fields to the register structures to hold these values and implements the necessary logic to fetch and store them using each hypervisor's API.

Register structure updates:

• Added xmm: [u128; 16] and mxcsr: u32 fields to the X86_64Regs struct to store XMM registers and MXCSR control state.

Todo:

• implement set registers
• Test on all the platforms. I tested on kvm but need to look at windows and msvh