zcash_client_backend: Make AccountId an associated type of `WalletR…

…ead`

This PR was extracted from zcash#1175
in order to make the changes to `zcash_client_backend` usable without
the additional generalizations to `zcash_client_sqlite` made by that PR.

Co-authored-by: Andrew Arnott <[email protected]>

zcash_client_backend/CHANGELOG.md

@@ -56,6 +56,9 @@ and this library adheres to Rust's notion of
     }`
   - `WalletSummary::next_sapling_subtree_index`
   - `wallet`:
+    - `HDSeedAccount`
+    - `ImportedAccount`
+    - `Account`
     - `propose_standard_transfer_to_address`
     - `create_proposed_transactions`
     - `input_selection`:
@@ -96,6 +99,34 @@ and this library adheres to Rust's notion of
   - `parse::Param::name`
 
 ### Changed
+- Several structs and functions had `AccountId` added as a generic type
+  parameter in order to decouple the concepts of an account identifier
+  and a ZIP-32 account index. Many APIs that previously referenced `zcash_primitives::zip32::AccountId` now reference the generic type. Impacted types and functions are:
+  - `zcash_client_backend::data_api::wallet::InputSelector::propose_transaction`
+  - `zcash_client_backend::data_api::wallet::propose_transfer`
+  - `zcash_client_backend::data_api::wallet::propose_standard_transfer_to_address`
+  - `zcash_client_backend::data_api::WalletRead::get_account_birthday`
+  - `zcash_client_backend::data_api::WalletRead::get_current_address`
+  - `zcash_client_backend::data_api::WalletRead::get_unified_full_viewing_keys`
+  - `zcash_client_backend::data_api::WalletRead::get_account_for_ufvk`
+  - `zcash_client_backend::data_api::WalletRead::get_wallet_summary`
+  - `zcash_client_backend::data_api::WalletRead::get_sapling_nullifiers`
+  - `zcash_client_backend::data_api::WalletRead::get_transparent_receivers`
+  - `zcash_client_backend::data_api::WalletRead::get_transparent_balances`
+  - `zcash_client_backend::data_api::WalletRead::get_account_ids`
+  - `zcash_client_backend::data_api::ScannedBlock`
+  - `zcash_client_backend::data_api::DecryptedTransaction`
+  - `zcash_client_backend::data_api::SentTransaction`
+  - `zcash_client_backend::data_api::SentTransactionOutput`
+  - `zcash_client_backend::data_api::WalletWrite::create_account`
+  - `zcash_client_backend::data_api::WalletWrite::get_next_available_address`
+  - `zcash_client_backend::decrypt::DecryptedOutput`
+  - `zcash_client_backend::decrypt::decrypt_transaction`
+  - `zcash_client_backend::scanning::scan_block`
+  - `zcash_client_backend::wallet::Recipient`
+  - `zcash_client_backend::wallet::WalletTx`
+  - `zcash_client_backend::wallet::WalletSaplingSpend`
+  - `zcash_client_backend::wallet::WalletSaplingOutput`
 - `zcash_client_backend::data_api`:
   - `BlockMetadata::sapling_tree_size` now returns an `Option<u32>` instead of
     a `u32` for future consistency with Orchard.
@@ -114,6 +145,8 @@ and this library adheres to Rust's notion of
   - `WalletSummary::new` now takes an additional `next_sapling_subtree_index`
     argument.
   - Changes to the `WalletRead` trait:
+    - Added associated type `AccountId`.
+    - Added `get_account` function.
     - `get_checkpoint_depth` has been removed without replacement. This is no
       longer needed given the change to use the stored anchor height for
       transaction proposal execution.
@@ -273,7 +306,7 @@ and this library adheres to Rust's notion of
 ### Removed
 - `zcash_client_backend::wallet`:
   - `ReceivedSaplingNote` (use `zcash_client_backend::ReceivedNote` instead).
-  - `input_selection::{Proposal, ProposalError}` (moved to
+  - `input_selection::{Proposal, ShieldedInputs, ProposalError}` (moved to
     `zcash_client_backend::proposal`).
   - `SentTransactionOutput::sapling_change_to` - the note created by an internal
     transfer is now conveyed in the `recipient` field.