Use Esplora's get_block_hash() method

[tnull]

Description

This PR makes use of the recently added get_block_hash() API method of the Esplora client.

Previously, we retrieved the entire header to extract the BlockHash. Funnily enough, the header was internally retrieved through a combination of getting hash by height and then getting the header by hash.

Notes to the reviewers

This is currently blocked on the next release of rust-esplora-client.

Changelog notice

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[rajarshimaitra]

Seems like this needs a new release of esplora-client?

[tnull]

This is currently blocked on the next release of rust-esplora-client.

Correct, as noted in the description. Feel free to add a corresponding tag.

[notmandatory]

The new esplora-client 0.2 was released today and will get updated in the upcoming bdk 0.24.0 milestone via #770. Since this PR doesn't look like an urgent change I added it to the 0.25.0 bdk milestone.

[tnull]

The new esplora-client 0.2 was released today and will get updated in the upcoming bdk 0.24.0 milestone via #770. Since this PR doesn't look like an urgent change I added it to the 0.25.0 bdk milestone.

Fine with both, really no urgency from my side. That said, I'll rebase as soon as #770 lands.

[afilini]

Sorry I missed this PR and did the same change in #770 (your deprecation notice was very helpful!).

I'm going to close this one since it won't be needed anymore, sorry for not noticing it before.