Integration tests

[shesek]

• Uses the fantastic bitcoind crate by @RCasatta to setup a bitcoind regtest environment

• Currently supports Bitcoin mode only, Liquid support is up next (a similar elementsd crate exists to setup an elements regtest environment)

  Support for Liquid mode was added.

• Currently covers the HTTP REST API (some basic tests for 14 endpoints) , testing the Electrum RPC server will be added later - either with electrum_client to test the RPC commands directly, or more fully e2e with an headless Electrum wallet (I did the later before for bwt)

  The tests now cover the Electrum RPC server too.

• I'm also looking to later implement e2e tests for the Esplora client-side web UI, using something like cypress.

  Available here: https://github.com/Blockstream/esplora/pull/362.

• Running with JSONRPC_IMPORT=1 speeds up the initial indexing which can be useful for local development.

• CI integration is still not implemented via Github Actions.

[shesek]

Added e2e tests for the Electrum RPC server using the headless Electrum wallet daemon (96b7b0f3ac78a561daaa32e1f864b98a8a6bb317).

[shesek]

Added support for testing in Elements/Liquid mode in d62f582224cc43a22d31cce524fd1c48b8af0a53 and 25c7e9e2e5305e6558c47088f8b4de8a4f99fd50, including tests for Elements-specific functionality: CT, asset issuance and signed dynafed blocks.

Next up are tests for the esplora web ui.

[shesek]

Implemented e2e browser tests for the esplora web ui in https://github.com/Blockstream/esplora/pull/362.

[shesek]

Rebased on top of #48.

[shesek]

Added Github Actions CI and rebased on top of #48.

Lacking further review, I will go ahead and merge this once #48 is in.

[shesek]

Reopened as #60.