add electrum support

[nicbus]

This PR adds support for Electrum as indexer.

bp-wallet has been modified so:

• a new electrum feature is available, adding required dependencies
• a new electrum indexer has been added
• a new any indexer and error have been added

bp-util has been modified so:

• a new --electrum <URL> option can be specified
• only one of --electrum and --esplora can be specified
• the short -e version for esplora has been dropped
• if an electrum URL is specified, electrum is used as indexer
• if an esplora URL or none is specified, esplora is used as indexer

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 268 lines in your changes are missing coverage. Please review.

Project coverage is 0.0%. Comparing base (8552e16) to head (35249ab).

Files	Patch %	Lines
src/indexers/electrum.rs	0.0%	224 Missing ⚠️
src/indexers/any.rs	0.0%	41 Missing ⚠️
src/indexers/esplora.rs	0.0%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##           master    #19    +/-   ##
======================================
  Coverage     0.0%   0.0%            
======================================
  Files           9     11     +2     
  Lines         932   1198   +266     
======================================
- Misses        932   1198   +266     

Flag	Coverage Δ
rust	0.0% <0.0%> (ø)

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[dr-orlovsky]

Great work. However, I dislike the idea of adding rust-bitcoin to the dependency list so much that I even did a refactoring of the electrum client to use BP libs instead of it: https://github.com/BP-WG/bp-electrum-client

rust-bitcoin takes so long to compile and breaks so much with each release... I know it's behind the feature gate, but in reality, we use --all-features in tests etc, so it will blow up the CI times at least.

Can you please update the dependency to use refactored electrum-client? It's API have not changed and will should work once you get rid of all (now unneeded) conversions to rust-bitcoin structures.

[nicbus]

Can you please update the dependency to use refactored electrum-client? It's API have not changed and will should work once you get rid of all (now unneeded) conversions to rust-bitcoin structures.

Refactored to use bp-electrum-client in place of electrum-client and dropping rust-bitcoin (and hex).

I set the PR as draft as IMO it makes sense to wait for a release of bp-electrum-client and the merge of BP-WG/bp-core#82 before proceeding with this one.

[dr-orlovsky]

LGTM, will do a more thorough review later. Since you confirm that the refactored electrum client works and does everything it is expected I will release it now

[dr-orlovsky]

bp-electrum-client v0.11.0-beta.5 released

[nicbus]

updated to use the released bp-electrum

[dr-orlovsky]

ACK 35249ab