Implement more space-efficient code managers

[alexrp]

SimpleCodeManager is functional but really not great. Due to the huge allocation granularity on Windows, it will cause considerable address space fragmentation when hooking multiple functions. This is a serious problem for us because, unlike the average 64-bit application, we actually need our code allocations to be near the code we're hooking.

We need two additional code managers:

• [x] PageCodeManager: Allocates from the OS using the system allocation granularity. Hands out a full page for each code allocation. Enforces W^X.
• [ ] BlockCodeManager: Allocates from the OS using the system allocation granularity. Hands out tiny blocks of memory for each code allocation. Always RWX (no W^X support).

Maybe also rename SimpleCodeManager to something like SparseCodeManager. Or just nuke it. 🤷

[alexrp]

PageCodeManager done in 0acd47dbfbfe20e7cf5ff3d7c68412e54a58aa29. SimpleCodeManager was nuked.