feat: Support serviceOverrides on the ListenerClass

[sbernauer]

Description

Part of #324 and stackabletech/issues#712.
Decision was in #330.

Needs stackabletech/operator-rs#1142 from operator-rs

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Release notes

Added:

You can now configure serviceOverrides on ListenerClass.spec.serviceOverrides similar to podOverrides on your stacklets. This enables you to make arbitrary modification to the created Services.

[NickLarsenNZ]

LGTM

[lfrancke]

I do know we had a decision about this and voted on it etc..
Just wondering: Does this also support objectOverrides?

[sbernauer]

The ListenerClass only describes how services should look like, so it only has a serviceOverrides.
The Listener however has objectOverrides.

We might be able to add objectOverrides to the ListenerClass as well, but that would make things a bit more complicated, as we would need to take objectOverrides from the ListenerClass as well as the Listener into account.