- `bitstring` started depending on `bitarray` in version 4.1 [0]
- that would mean one additional dependency for us (from yet another maintainer), which is not even pure python
- we only use bitstring for bolt11-parsing
- hence this PR rewrites the bolt11-parsing and removes `bitstring` as dependency
- note: I benchmarked lndecode using [1], and the new code performs better,
taking around 80% time needed for old code (when using bitstring 3.1.9, pure python).
Though the variance is quite large in both cases.
[0]: 95ee533ee4/release_notes.txt (L108)
[1]: d7597d96d0
I decided to use the stdlib (hashlib) instead of libsecp for this,
as it is simple enough, and the former is faster on my PC.
Added a unit test that compares the two.
The transaction dict can also contain PSBTs (in addition to complete raw hex txs).
This is the case if the user has saved a partial (e.g. unsigned) tx as local into the history.
fixes https://github.com/spesmilo/electrum/issues/8913
