Make download endpoint configurable

[tnull]

Closes #106.

In this PR we make the download endpoint configurable. If this is accepted, I'll see to open an equivalent PR towards electrsd.

[RCasatta]

not yet sure why we have an error in the ci for 1.41.1...

[tnull]

not yet sure why we have an error in the ci for 1.41.1...

Mh, seems linux-raw-sys has an MSRV of 1.48.0, but I'm currently not seeing where this dependency is coming from, as it's not listed in cargo tree --all-features.

[RCasatta]

This MR is clearly not causing the issue with the CI

I would have preferred the "f typo" commit was squashed, but I would like to avoid the roundtrip for it. I am going to merge

ACK 56f2321

[RCasatta]

not yet sure why we have an error in the ci for 1.41.1...

Mh, seems linux-raw-sys has an MSRV of 1.48.0, but I'm currently not seeing where this dependency is coming from, as it's not listed in cargo tree --all-features.

apparently the dep linux-raw-sys is in the dep tree only for 1.41.1 but that rust toolchain hasn't a tree subcommand... I manually searched for it, MR coming...