ICorDebugProcess5::EnumerateGCReferences doesn't include finalizer queue references

### Description

During code review I noticed that we have missing functionality. The ICorDebugProcess5::EnumerateGCReferences API claims that it will provide a full set of GC roots but it doesn't enumerate the finalizer queue. The DacRefWalker type has a parameter `BOOL walkFQ` that implies it should support this but nothing reads the mWalkFQ variable it sets. There is also some code in DacRefWalker::Next() that would iterate using mFQCurr and mFQEnd but nothing sets those fields to non-NULL values so the loop body is dead code.

PR #129345 removed some of the dead code making the missing behavior more obvious.

### Reproduction Steps

I identified the issue from code review and didn't test a repro. I assume it could be reproed by writing a debugger using ICorDebug, attach to a process that has an object rooted by the finalizer queue, and then run ICorDebugProcess5::EnumerateGCReferences.

### Expected behavior

ICorDebugProcess5::EnumerateGCReferences would enumerate the object in the finalizer queue

### Actual behavior

ICorDebugProcess5::EnumerateGCReferences would not enumerate the object in the finalizer queue

### Regression?

Git history suggests this codepath has been dead for at least the entire time the source has been open and perhaps it never worked.

### Known Workarounds

_No response_

### Configuration

Any version of .NET Core, any OS, any architecture

### Other information

_No response_

Start at ICorDebugProcess5::EnumerateGCReferences and trace how DacRefWalker handles finalizer-queue traversal. Inspect mWalkFQ, mFQCurr, and mFQEnd, including the changes from PR #129345. Done means a debugger using the API enumerates objects rooted by the finalizer queue, with behavior checked against a process containing such an object.

Written by the indexing model from the issue text.