Ithaca (replacement)

Context

New snapshot of Ithaca protocol (replacing !4056 (merged)) that includes fix from !4064 (merged).

Created using the following commands.

1. Snapshot protocol on proto-i branch.

$ git checkout a03b7dbd79d3262ee1a15c7d11af1225a098cb9a # head of proto-i branch
$ ./scripts/snapshot_alpha.sh ithaca_012
$ git add --all
$ git stash

2. Revert previous one.

$ git checkout master
$ git checkout -b ithaca
$ git revert --no-edit d70a4bb20^..3a10722a # previous snapshot

3. Add and link protocol.

$ git stash pop
# resolve conflict in docs/index.rst
$ git add docs/index.rst
$ git commit -m "Protocol: Ithaca"

$ dune exec scripts/declare-new-protocol-unit-test/main.exe -- 012 PsiThaCa
$ ./scripts/link_protocol.sh src/proto_012_PsiThaCa
$ git add --all
$ git commit -m "Build: link Ithaca"

4. Redo followup changes from !4056 (merged).

$ git cherry-pick a07cbcc4^..3a10722a
# amend last commit, updating long and short hash

Manually testing the MR

Please follow instructions in !4064 (merged), replacing hash in the patch for src/bin_node/node_config_file.ml with new value: PsiThaCaT47Zboaw71QWScM8sXeMM7bbQFncK9FLqYc6EKdpjVP.