Implement basic paging support

[maxmitchelson]

Implement basic support for paging and physical frame allocation in the kernel. This is an initial step toward securing memory regions and enabling future features such as a heap allocator. The Limine bootloader already enables paging for us, but more control over paging is necessary.

Requirements:

• Set up an x86_64-compatible paging system.
• Prioritize support for 4-level paging, with optional support for 5-level paging.
• Implement a fully-featured frame allocator using the buddy system #2
• Ensure proper handling of memory protection (marking regions as writable, executable, etc.).

Useful resources

• The Limine documentation to ensure proper paging setup: PROTOCOL.md
• Relevant osdev wiki articles: Setting up paging ; Page Frame Allocation
• Articles from phil-opp's rust osdev blog: Introduction ; Implementation

[maxmitchelson]

Volume 2, Section 5 from AMD64's architecture documentation is extremely useful for more detailed information on paging implementation: AMD64 Architecture Programmer's Manual, Volumes 1-5.

edit: resource changed location

[maxmitchelson]

While the most up-to-date changes in 09bad0a contain foundational components for page management (creating new ones, writing/reading page tables and their entries,...) the current frame allocator is way too bare-bones (only allocating sequentially, creating major external fragmentation and not supporting deallocations) for a "true" page allocator. I've split this into its own issue with #2 to better track progress on memory allocation.