[Build System Rewrite] Refactored `Makefile`

[Icedude907]

• [ ] Depends on / Includes #1949

The commit 2198ca31c7a5239176b92bc577408bc1e7715cd4 changes the makefile in numerous ways with the goal of making it easier to understand for the end user. Much of the code previously spread out and repeated has been unified into workable chunks.

This one might be a bit of a pain for downstream projects to merge but many of my subsequent changes will need it.