Using block undo data [...] we can now show fee information for each transaction in a block without the need for additional -txindex and/or a ton of costly lookups. For a start we'll add transaction fee information to getblock verbosity level 2. This comes at a negligible speed penalty (<1%).
Backport of core#18772.
Note that we already had a test for the getblock verbose output, so this
one is added using a more explicit name (D2589).
Depends on D12425.