Add PodListeners

[nightkr]

Description

This is a new metadata object written in stackabletech/listener-operator#100, which gives external entities the same address information as the pod volume provides internally.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author
- [x] Changes are OpenShift compatible
- [x] CRD changes approved
- [x] Integration tests passed (for non trivial changes)

# Reviewer
- [x] Code contains useful comments
- [x] (Integration-)Test cases added
- [x] Documentation added or updated
- [x] Changelog updated
- [x] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[fhennig]

Heyho, sorry to be a PITA about the docs, but I had some ideas for how things could be documented better.

[fhennig]

🚢

[fhennig]

Uhm technically I guess

CRD changes approved

the changes would need to be approved?

But maybe we can already merge this as I think it'll be an uncontroversial change. But can you put it on the agenda for the arch meeting?

[nightkr]

Good point, I'll add it to the meeting.

[siegfriedweber]

LGTM (except if you want to set the plural of PodListeners to podlisteners instead of podlistenerses as discussed in stackabletech/listener-operator#100 (comment))

[maltesander]

LGTM! I like the current naming approach. Lets wait for @siegfriedweber and @Techassi still?