Refactor pa_from_va to handle guest to host address translation

[memN0ps]

This commit refactors the pa_from_va function to improve clarity and ensure proper handling of guest to host address translation using EPT (Extended Page Table). The function would crash if translate_guest_pa_to_host_pa is used due to pre-allocated page tables in the hook_manager that are not passed to this function (not required regardless due to 1:1 mapping).

Changes:

• Translate guest virtual address (VA) to guest physical address (PA) using guest's CR3.
• Translate guest PA to host PA using EPT, even in a 1:1 mapping scenario, for demonstration purposes and to accommodate potential future changes to Paging/EPT.
• Add detailed comments explaining potential issues and the reasoning behind the translation steps.

This function is used in many places across the hypervisor for reading guest memory.