Do not allow short lockups to vote on proposals for longer liquidity deployment

[dusan-maksimovic]

Description

If users want to vote for proposals with longer liquidity deployment duration, then their lockups must have at least some voting power in round that precedes the round in which the liquidity will be returned. For example, if there is a proposal in round 1 requesting liquidity to be deployed with them for 3 rounds, then users can vote for such proposal only with lockups that are ending in round 4 or later.

Changes had to be made in vote() and lock_tokens() functions because of the "automatic" voting that happens when user locks more tokens, if user already voted for some proposal in current round.

---

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• Targeted the correct branch
• Included the necessary unit tests
• Added/adjusted the necessary interchain tests
• Added a changelog entry in .changelog
• Compiled the contracts by using make compile and included content of the artifacts directory into the PR
• Regenerated front-end schema by using make schema and included generated files into the PR
• Updated the relevant documentation or specification
• Reviewed "Files changed" and left comments if necessary
• Confirmed all CI checks have passed