[MonoVM] Fix calculation of code size for AOT assemblies mixing JIT and LLVM

[filipnavara]

Fixes #56100

Here's a little bit of background on the problem. When multiple AOT modules got linked into the same executable for iOS/MacCatalyst the LLVM and JIT code sections of different modules got interleaved. The resulting AOT module info looks something like this:

JIT start: 0x101002100 JIT end: 0x1010035e0
LLVM start: 0x104c027c8 LLVM end: 0x104c603e8
Sorted methods:
  0x101002250
  0x101002390
  0x101002470
  0x104c027c8
  0x104c027e0
  ...

The previous code incorrectly assumed that the third method had a code size 0x104c027c8 - 0x101002470. When inserted into lookup table any of the AOT code inside the range 0x1010035e0 (JIT code end) - 0x104c027c8 (LLVM code start) would incorrectly end up being mapped to the last JIT method.

(Note: The JIT name here is misleading.)

[lambdageek]

/backport to release/6.0

[github-actions]

Started backporting to release/6.0: https://github.com/dotnet/runtime/actions/runs/1190642261

[imhameed]

The "Build MacCatalyst x64 Release AllSubsets_Mono" failures are also present in a completely unrelated PR. Ditto for "Build iOSSimulator x64 Release AllSubsets_Mono".