feat: create k8s_service_info library

[DnPlas]

This library provides functionality for sharing Kubernetes Service information using the k8s-service relation interface. Please refer to #2 for details.

NOTE: please merge after #4

Fixes #2

[orfeas-k]

I did a quick pass too and left some minor comments.

[orfeas-k]

Should we add some basic repo settings to this regarding merging and protection? Since this is something our charms will use. I see

# PR page
Require approval from specific reviewers before merging
# main repo page
Your main branch isn't protected
Protect this branch from force pushing or deletion, or require status checks before merging. [View documentation.](https://docs.github.com/repositories/configuring-branches-and-merges-in-your-repository/managing-rulesets/about-rulesets)

[ca-scribner]

added some comments but generally looks promising!

[DnPlas]

Should we add some basic repo settings to this regarding merging and protection? Since this is something our charms will use. I see

# PR page
Require approval from specific reviewers before merging
# main repo page
Your main branch isn't protected
Protect this branch from force pushing or deletion, or require status checks before merging. [View documentation.](https://docs.github.com/repositories/configuring-branches-and-merges-in-your-repository/managing-rulesets/about-rulesets)

Good catch, I have added a branch protection rule for main.

[ca-scribner]

added some more review comments

[ca-scribner]

Added a few things to look into as comments

[ca-scribner]

Small thing in the tests, otherwise lgtm

[ca-scribner]

lgtm! ty @DnPlas!