Implement CLRDataMethodDefinition IL extent APIs in cDAC

[Copilot]

Implements IL extent enumeration and representative entry-address lookup for CLRDataMethodDefinition, replacing legacy fallback behavior.

• Implementation

  • Adds StartEnumExtents, EnumExtent, EndEnumExtents, and GetRepresentativeEntryAddress.
  • Preserves legacy DAC semantics for tiny/fat IL headers and single-shot enumeration.
  • Reads fixed-format IL fields as little-endian across target architectures.

• Validation

  • Adds CanFallback() gates to legacy debug cross-validation.
  • Covers invalid arguments, missing IL, and tiny/extended-fat headers.

Note

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