[Off-chain] feat: observable utils

[bryanchriswhite]

Summary

Adds:

• ForEach() calls the given function for each notification (like Map() without an destination)
• Filters:
  • EitherError() filters out only eithers with error populated and maps the error to the destination
  • EitherSuccess() filters out only eithers with value populated and maps the value to the destination
• LogErrors() logs notifications from the given error observable

Human Summary

AI Summary

Summary generated by Reviewpad on 09 Nov 23 19:54 UTC

This pull request includes three changes:

1. Added a new file pkg/observable/filter/either.go, which provides functions for filtering and mapping an observable of an either type. It includes functions EitherError and EitherSuccess for filtering eithers based on whether they are populated with errors or values, respectively.

2. Added a new file pkg/observable/logging/logging.go, which includes functions for logging errors received from an observable. The LogErrors function logs all errors received from the observable.

3. Modified the existing file pkg/observable/channel/map.go to include a new type ForEachFn and a new function ForEach. The ForEach function applies the given forEachFn to each notification received from the observable, similar to Map, but without publishing to a destination observable. It is useful for side effects and is a terminal observable operator.

Issue

• #{ISSUE_NUMBER}

[Explain the reasoning for the PR in 1-2 sentences. Consider adding a link or a screenshot.]

Type of change

Select one or more:

• New feature, functionality or library
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Testing

• Run all unit tests: make go_develop_and_test
• Verify Localnet manually: See the instructions [here](TODO: add link to instructions)

Sanity Checklist

• I have tested my changes using the available tooling
• I have performed a self-review of my own code
• I have commented my code, updated documentation and left TODOs throughout the codebase

[Olshansk]

Couple comments but very nice and clean!

[Olshansk]

Great comments, naming, design, and everything across the board