Add filtering to KV method returning all keys

[saurabhojha]

Resolves: #766

This PR introduces the kvStore_KeysWithFilters function to the kvStore API. This function allows users to retrieve keys from a key-value store bucket that match one or more subject-like filters. The function helps in querying specific keys based on patterns, enhancing the flexibility and usability of key retrieval.

[kozlovic]

Thank you for the contribution. I made some comments. Lots of them are just code style, but the most important is to not duplicate the code for the main function.

[kozlovic]

Some more modifications needed.

[kozlovic]

Before I continue the review, please make sure that your changes in the core Keys() function are needed. I am not sure they are.

[kozlovic]

By the way, you may want to combine all subsequent changes in a single commit before pushing it (to reduce CI runs).

[saurabhojha]

Hi @kozlovic , made the changes you requested. Please let me know if anything else has to be changed.

[kozlovic]

Let's move the options around.

But, this brings the question: @levb, had you consider having the filter options as part of the kvWatchOptions instead of adding a kvStore_WatchMulti()? In PR #750, I don't see me suggesting that, but since this has never been released yet, it would be possible to change it. If that had been the case, there would not even be a need for a new kvStore_KeysWithFilters() API, since kvStore_Keys() accepts a kvWatchOptions, we could have passed the filters through that (we would have needed to change a bit to use filters if specified and call Watch() - or if documenting that Watch() uses filters over provided key, no change at all).

[kozlovic]

@saurabhojha @levb My comment about passing filters through options may be a moot point if the ADR asks libraries to add a new API.

[kozlovic]

LGTM! But I will let @levb decide if we merge as-is or if he wants to revisit the WatchMulti or not. If we do merge this PR, I would recommend the "squash on merge", since there are a lot of commits on that one.

[levb]

@saurabhojha @kozlovic I've been quite sick the last couple days, I'll review this soon. @saurabhojha Thank you for the contribution!

[kozlovic]

@levb So sorry to hear that. Please rest, there is really no urgency in reviewing this PR.

[saurabhojha]

@levb take care and please rest. this can be reviewed later as well.

[levb]

Let me confirm with @Jarema, I like the simplification of using kvWatchOptions.

[levb]

After discussing with @Jarema 1/5 we should mimic the Go API, and have these as separate methods. In a future release we'd attempt to simplify the multiple subjects/filters interface.