Interpreter GC info stage 2: Generate empty GC info and add baseline implementation of EnumGcRefs

[kg]

Depends on #113900, currently based on it

• Modify GcInfoEncoder and its sibling files so that they can be successfully linked into the interpreter module; added new gcinfohelpers.h file with support code and macros
  • This required disabling a lot of logging and assertion code temporarily, so we need to figure out the right approach for that stuff before this lands.
  • There are a couple load-bearing asserts inside the encoder that need to be evaluated for safemath to not explode in debug builds of crossgen2.
  • I replaced all the existing assertions and logging with new GCINFO_ASSERT and GCINFO_LOG macros so we can easily come back and change this later and reduce the blast area of any weird tricks we pull, instead of redefining _ASSERTE or LOG.
• Add new InterpreterGcInfoEncoder and InterpreterGcInfoDecoder
• Link gcinfo into the interpreter so the encoder and decoder are available
• At the end of interpreter method compilation, use InterpreterGcInfoEncoder to generate gc info for the method. EnumGcRefs will fail if we don't do this. We need to specifically do this at the end after the code header has been allocated, we can't do it earlier.
• Add placeholder implementation of EnumGcRefs for the interpreter, modeled on the existing one for the JIT.
• Add placeholder interp opcode that triggers a GC, so that we can easily test gcinfo and stackwalking in various interpreter scenarios.

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