[#148] Improve batching

[lierdakil]

Description

Problem: a lot of initial setup in tests can be batched, considerably speeding up network tests.

Solution: do that.

This replaces individual address setup with a structure in some tests. This is a little bit wasteful, but barely so, as addresses should be reused.

Related issue(s)

Resolves #148

✅ Checklist for your Pull Request

Related changes (conditional)

• Tests

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from
    silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README
    • Haddock
  • I updated changelog unless I am sure my changes are
    not essential.

Stylistic guide (mandatory)

• My commits comply with the policy used in Serokell.
• My code complies with the style guide.

✓ Release Checklist

• I updated the Gas / Transaction costs table in the README.
• I updated the version number in package.yaml.
• I updated the changelog and moved everything
  under the "Unreleased" section to a new section for this release version.
• (After merging) I created a new entry in the releases page,
  with a summary of all user-facing changes.
  • I made sure a tag was created using the format vX.Y.Z
  • I attached the following artifacts from buildkite
    • stablecoin-client
    • stablecoin.fa1.2.tz
    • stablecoin.tz

[lierdakil]

@pasqu4le I'm pinging you for review, but as I mentioned previously, this doesn't seem to be worth it, there's barely any difference.

If there's any improvement at all, it's entirely drowned out by the noise.

[pasqu4le]

I'm closing this as the changes make little difference, then