refactor!(chain): Unify ChangeSet nomenclature

[danielabrozzoni]

Solves #1022

Changelog notice

Rename indexed_tx_graph::IndexedAdditions to indexed_tx_graph::ChangeSet
Rename indexed_tx_graph::IndexedAdditions::graph_additions to indexed_tx_graph::ChangeSet::graph
Rename indexed_tx_graph::IndexedAdditions::index_additions to indexed_tx_graph::ChangeSet::indexer
Rename tx_graph::Additions to tx_graph::ChangeSet
Rename keychain::DerivationAdditions to keychain::ChangeSet
Rename CanonicalTx::node to CanonicalTx::tx_node
Rename CanonicalTx::observed_as to CanonicalTx::chain_position
Rename LocalChangeSet to WalletChangeSet
Rename LocalChangeSet::chain_changeset to WalletChangeSet::chain
Rename LocalChangeSet::indexed_additions to WalletChangeSet::indexed_tx_graph
Rename LocalUpdate to WalletUpdate
Make TxGraph::determine_changeset pub(crate)
Add TxGraph::initial_changeset
Add IndexedTxGraph::initial_changeset
Remove TxGraph::insert_txout_preview
Remove TxGraph::insert_tx_preview
Remove insert_anchor_preview
Remove insert_seen_at_preview

Notes to reviewers

I'm not sure whether we want to keep TxGraph::determine_changeset public or not

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

[notmandatory]

LGTM! much easier to read using the same nomenclature across the code base. I added a couple comments/questions. I think this should go in before #1048 and then I'll rebase that PR on these changes.

[evanlinjin]

LGTM too. I can ACK and merge after wording changes as mentioned by @notmandatory.

[LLFourn]

Haven't reviewed but got a note here: #1060 (comment) that TxGraph doesn't have an "initial_changeset" method to dump the full state as a changeset. It should in order to be consistent. Same with IndexedTxGraph. Can we also make sure all changeset types are must_use (except for the wallet one).

[LLFourn]

Approved as it is but I've made a few extra renaming suggestions and I do think now is the time to create initial_changeset methods for the tx graphs. The tx graph one could probably be implemented something like:

fn initial_changeset(&self) -> ChangeSet {
    Self::default().apply_update(self.clone())
}

but for IndexedTxGraph you might have to add a initial_changeset method to the Indexer trait to get it done properly.

[danielabrozzoni]

I rebased and fixed the review comments. I'm now working on adding initial_changeset for the tx_graph and the indexed_tx_graph, but since this PR is holding up #1040, feel free to merge before I'm done and I'll open a new PR

[danielabrozzoni]

Also, every ChangeSet is #[must_use] apart from the local_chain one, but since it's just a type alias, when I tried to add it the compiler warned me that it would have no effect:

   Compiling bdk_chain v0.5.0 (/home/daniela/Developer/bitcoindevkit/bdk/crates/chain)
warning: `#[must_use]` has no effect when applied to a type alias
  --> crates/chain/src/local_chain.rs:14:1
   |
14 | #[must_use]
   | ^^^^^^^^^^^
   |
   = note: `#[warn(unused_attributes)]` on by default

[danielabrozzoni]

Ok, this took less than what I expected :) I just pushed 4ac9c03, adding initial_changeset to tx_graph and indexed_tx_graph.

[notmandatory]

Looks good. ACK 4ac9c03

[vladimirfomene]

Review ACK 4ac9c03. Feel free to push the TxGraph refactoring to another PR.

[evanlinjin]

ACK 4ac9c03

Looks good. My comments are regarding documentation, variable naming and minute implementation details (things that are not mission-critical and can be addressed later).

[notmandatory]

@danielabrozzoni looks like some small but useful suggestions so I'll wait until you've had a chance to address them before merging.

[LLFourn]

ACK 4ac9c03

[danielabrozzoni]

Thanks for the reviews! Updated, and pushed a commit on top to fix the CI

[evanlinjin]

ACK 62f2531