[wallet] Kill accounts

This commit does the following changes:

- [wallet] Remove 'account' argument from GetLegacyBalance()
  - GetLegacyBalance() is never called with an account argument.
    Remove the argument and helper functions.
- [wallet] Remove CWallet::ListAccountCreditDebit()
  - Function no longer used.
- [wallet] Remove AccountMove()
  - Function no longer used.
- [wallet] Remove AddAccountingEntry()
  - Function no longer used.
- [wallet] Remove GetAccountCreditDebit()
  - Function no longer used.
- [wallet] Don't rewrite accounting entries when reordering wallet transactions.
 - Accounting entries are deprecated. Don't rewrite them to the wallet
   database when re-ordering transactions.
- [wallet] Remove WriteAccountingEntry()
  - Function no longer used.
- [wallet] Don't read acentry key-values from wallet on load.
- [wallet] Remove ListAccountCreditDebit()
  - Function no longer used.
- [wallet] Remove CAccountingEntry class
  - No longer used
- [wallet] Remove GetLabelDestination
  - Function no longer used.
- [wallet] Delete unused account functions
  - ReadAccount
  - WriteAccount
  - EraseAccount
  - DeleteLabel
- [wallet] Remove fromAccount argument from CommitTransaction()
- [wallet] Remove strFromAccount.
  - No longer used.
- [wallet] Remove strSentAccount from GetAmounts().
  - No longer used.
- [wallet] Update zapwallettxes comment to remove accounts.
- [wallet] Remove CAccount
  - No longer used
- [docs] fix typo in release notes for PR 14023

doc/release-notes-14023.md

@@ -1,5 +1,5 @@
-Accout API removed
-------------------
+Account API removed
+-------------------
 
 The 'account' API was deprecated in v0.17 and has been fully removed in v0.18.
 The 'label' API was introduced in v0.17 as a replacement for accounts.