label_selector::convert_label_selector_to_query_string && pod_utils::pod_matches_multiple_label_values should return all Errors in a list instead of one-by-one

[lfrancke]

Currently convert_label_selector_to_query_string will check the passed LabelSelector and as soon as it hits any error it will return that error.
There might be more than one error in the LabelSelector though.

We'd like to change the Error (InvalidLabelSelector) to contain a list of strings instead of a single string and return all errors in one go.

An example of how this could be handled can be found in the Zookeeper Operator:
https://github.com/stackabletech/zookeeper-operator/blob/ffd0d3d5fc47d0f9878f3675eeaae741ca09483b/crd/src/util.rs#L164

[lfrancke]

@teozkr I assume this is not relevant for us anymore, the whole module might have been removed?

If my assumption is correct: Could you close this issue?