Additional features for analyze_snapshot tool #47924

Recently added in https://dart-review.googlesource.com/c/sdk/+/221087/ is a executable target build alongside the SDK tree that will allow for a stand-alone static analysis tool that will be able to parse snapshots generated by the current version of the SDK in a maintainable way that doesn't require manual upkeep to correct for breaking changes between the snapshot binary layout in different versions.

Currently basic support is added for class/function table metadata as well extracting string reference information.

This issue will track updates/checklists for additional features to be added.

• Class/Function table metadata
• Global Object Pool data
  • kOneByteString
  • kTwoByteString
• Process Dispatch Table entries
• Automatically parse VM init flags from snapshot
• Data Export formats
  • JSON
  • stdout "Pretty Print"