Upgrade core MEMOIR functionality to LLVM18

[tommymcm]

This issue will track progress on upgrading MEMOIR to LLVM18.

Once closed, the current main branch will be renamed to v9 and v18 will become main.

General problems that fall under this issue:

• [x] Migrate to new pass manager
• [x] Handle opaque pointers by default, this will require either metadata or new API calls for typing

[tommymcm]

Current Design for PassManager updates

• Declarations for Pass structs go in compiler/memoir/passes/Passes.hpp
• Each pass is registered in compiler/memoir/passes/src/Passes.cpp, along with required dependencies.

[tommymcm]

PassManager design changed to single source:

In compiler/memoir/Passes.def, register your pass with PASS(<scope>, <class>, <name>, <args>...) or analysis with ANALYSIS(<scope>, <class>, <result>, <args>...).

Where:

• <scope> is one of Module or Function
• <class> is the name of the class that implements the pass/analysis
• <name> is the name used to run the pass from the command line
• <result> is the type of the result returned from the analysis
• <args>... are additional arguments to be used when constructing the class

[tommymcm]

Everything except for RangeAnalysis, LiveRangeAnalysis, DeadElementElimination has been updated.

Those features rely on NOELLE, so we must wait until they are ready.

They are currently disabled by default, otherwise v18 can be considered as rc1.

[tommymcm]

Completed with 077073d