refactor(chain)!: remove `inner` method from KeychainTxOutIndex
It's desirable to have the inner SPK index internal to the
`keychain_txout` module, which aims to provide views into
the set of revealed SPKs for a given keychain.
The inner index also functions as a cache of unrevealed SPKs,
i.e. the lookahead. We test the functionality of the lookahead
by checking the value returned from
`KeychainTxOutIndex::spk_at_index` matches the SPK derived by
the descriptor at that index for indices ranging from the
last revealed to the expected last stored.
projects / bdk / commit