feat: add MsgSupplyCollateral

[toteki]

This might or might not be okay to merge in a minor version (due to adding a message type). Supports a common frontend use case.

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[toteki]

This PR should be evaluated for inclusion in v3.1.0

[robert-zaremba]

I don't think we need it. API, especially on proto level, should not have redundancy when possible.
The same effect can be achieved with one transaction with multiple messages.

[robert-zaremba]

this could have unintended consequences if we feed them into MsgServer (I'm not 100% sure).

You don't go through MsgServer, and no need to check signatures. You directly call the handler.
In fact even if you would go through MsgServer (which is not clearly supported today), it won't check signatures nor call ValidateBasic (which is happening at different stage)

[robert-zaremba]

pre-approving. See #1479 (comment) . That would be my preference, but I'm not against using the current way. I just prefer to avoid possible duplications.

[codecov-commenter]

Codecov Report

Merging #1479 (41e932a) into main (4519faf) will decrease coverage by 0.50%.
The diff coverage is 13.95%.

❗ Current head 41e932a differs from pull request most recent head 55a5d3e. Consider uploading reports for the commit 55a5d3e to get more accurate results

@@            Coverage Diff             @@
##             main    #1479      +/-   ##
==========================================
- Coverage   52.75%   52.25%   -0.51%     
==========================================
  Files          71       71              
  Lines        6750     6834      +84     
==========================================
+ Hits         3561     3571      +10     
- Misses       2920     2994      +74     
  Partials      269      269              

Impacted Files	Coverage Δ
x/leverage/client/cli/tx.go	0.00% <0.00%> (ø)
x/leverage/keeper/msg_server.go	0.95% <0.00%> (-0.22%)	⬇️
x/leverage/types/tx.go	0.00% <0.00%> (ø)
x/leverage/client/tests/tests.go	100.00% <100.00%> (ø)