feat: add query for getting all assigned keys

[freak12techno]

Description

Closes: #984

Adds provider query to fetch all assigned keys (either all of them, or filtered by consumer chain ID).
This is quite an alpha version that was never tested yet, please treat it accordingly.

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Author Checklist

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• Included the correct type prefix in the PR title
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I have...

• confirmed the correct type prefix in the PR title
• confirmed ! the type prefix if the change is state-machine breaking
• confirmed this PR does not introduce changes requiring state migrations, OR confirmed migration code has been added to consumer and/or provider modules
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
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[mpoke]

@freak12techno please note this similar PR #1503

[freak12techno]

@mpoke whoops, didn't notice that one. Do you think it's worth having what I did then?

[mpoke]

whoops, didn't notice that one. Do you think it's worth having what I did then?

@freak12techno Only if there is a use case that cannot be covered with the existing query.

[mpoke]

@freak12techno #1503 was merged and it's part of ICS v3.3.0, which will end up on Gaia v15 (the next release on Gaia). Please let us know if that is sufficient to close #984 and the corresponding Gaia issue cosmos/gaia#2555.

[freak12techno]

@mpoke I think that's sufficient, feel free to close