feat: implement MaxCollateralShare

[toteki]

Description

closes: #1093

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[codecov-commenter]

Codecov Report

Merging #1329 (008fd50) into main (1982eb7) will decrease coverage by 0.01%.
The diff coverage is 54.63%.

@@            Coverage Diff             @@
##             main    #1329      +/-   ##
==========================================
- Coverage   51.86%   51.85%   -0.02%     
==========================================
  Files          68       69       +1     
  Lines        6677     6754      +77     
==========================================
+ Hits         3463     3502      +39     
- Misses       2947     2979      +32     
- Partials      267      273       +6     

Impacted Files	Coverage Δ
x/leverage/keeper/limits.go	15.62% <15.62%> (ø)
x/leverage/keeper/collateral.go	65.45% <64.28%> (+3.48%)	⬆️
x/leverage/keeper/keeper.go	66.80% <87.50%> (+0.56%)	⬆️
x/leverage/keeper/grpc_query.go	61.14% <100.00%> (+0.44%)	⬆️

[robert-zaremba]

We decided to implement MaxCollateralShare as a % value

[robert-zaremba]

overall looks good. Let's don't calculate GetTotalCollateral twice.

[robert-zaremba]

pre-approving. Please look at the comments.