Burn state handling in the Clarity VM

[obycode]

Description

In Nakamoto, a transaction can access the current burn block, while in epoch 2.x, it can only access the burn block of its parent. This changeset updates the behavior, so that every block in a tenure, including the first block, can access the burn block information of the tenure's burn block.

Note, this is built off of #4745 -- only the last 4 commits are specific to this new work. It should be reviewed after that one is merged.

Applicable issues

• fixes #4333

Checklist

• [x] Test coverage for new or modified code paths
• [x] Changelog is updated
• [x] Required documentation changes (e.g., docs/rpc/openapi.yaml and rpc-endpoints.md for v2 endpoints, event-dispatcher.md for new events)
• [x] New clarity functions have corresponding PR in clarity-benchmarking repo
• [x] New integration test(s) added to bitcoin-tests.yml