multihop: some improvements (naming, documentation, errors)

[crodriguezvega]

Description

Some (hopefully) improvements to align with idc-go's code guidelines (e.g. regarding error reporting). Renamed some variables, functions to (hopefully) more clarifying names (at least for me 😄). Added extra comments and godocs.

I will open more PRs as I continue to go through the code.

closes: #XXXX

Commit Message / Changelog Entry

type: commit message

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Before we can merge this PR, please make sure that all the following items have been checked off. If any of the checklist items are not applicable, please leave them but write a little note why.

• [ ] Targeted PR against correct branch (see CONTRIBUTING.md).
• [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• [ ] Code follows the module structure standards and Go style guide.
• [ ] Wrote unit and integration tests.
• [ ] Updated relevant documentation (docs/) or specification (x/<module>/spec/).
• [ ] Added relevant godoc comments.
• [ ] Provide a commit message to be used for the changelog entry in the PR description for review.
• [ ] Re-reviewed Files changed in the Github PR explorer.
• [ ] Review Codecov Report in the comment section below once CI passes.