Merge bitcoin#29553: assumeutxo: Add dumptxoutset height param, remov…

…e shell scripts

94b0adc rpc, refactor: Prevent potential race conditions in dumptxoutset (Fabian Jahr)
e868a6e doc: Improve assumeutxo guide and add more docs/comments (Fabian Jahr)
b29c21f assumeutxo: Remove devtools/utxo_snapshot.sh (Fabian Jahr)
20a1c77 contrib: Remove test_utxo_snapshots.sh (Fabian Jahr)
8426850 test: Test for dumptxoutset at specific height (Fabian Jahr)
993cafe RPC: Add type parameter to dumptxoutset (Fabian Jahr)
fccf4f9 RPC: Extract ReconsiderBlock helper (Fabian Jahr)
446ce51 RPC: Extract InvalidateBlock helper (Fabian Jahr)

Pull request description:

  This adds a height parameter to the `dumptxoutset` RPC. This internalizes the workflow that was previously done by scripts: roll back the chain to the height we actually want the snapshot from, create the snapshot, roll forward to the real tip again.

  The nice thing about internalizing this functionality is that we can write tests for the code and it gives us more options to make the functionality robust. The shell scripts we have so far will be more cumbersome to maintain in the long run, especially since we will only notice later when we have broken them. I think it's safe to remove these `test_utxo_snapshots.sh` as well when we have this option in `dumptxoutset` because we have also added some good additional functional test coverage for this functionality.

ACKs for top commit:
  Sjors:
    re-utACK 94b0adc
  achow101:
    ACK 94b0adc
  mzumsande:
    ACK 94b0adc
  pablomartin4btc:
    re-ACK 94b0adc

Tree-SHA512: a4c9af5f687d1ca7bfb579a36f363882823386b5fa80c05de531b05a2782b5da6ff5baf3ada4bca8f32f63975d86f1948175abed9affe51fc958472b5f838dab