This transaction broke past versions of `rust-bitcoin` and LND so this
adds a test to avoid reintroducing the problem in the future.
See also https://github.com/romanz/electrs/issues/783
In order that we can safely change/maintain de/serialization code we
need to have regression tests with hard coded serializations for each
type that implements serde.
It is enough to test a single serde data format, use JSON for `opcodes`
and bincode for other types.
Do regression testing in a newly added `tests` module.