feat: ADR-006: Subspaces module

[RiccardoM]

Description

This PR implements ADR-006: Subspaces module adding a new x/subspaces module.

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Author Checklist

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I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
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• confirmed all CI checks have passed

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I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov]

Codecov Report

Merging #728 (6c6e53b) into master (e387353) will increase coverage by 1.89%.
The diff coverage is 83.91%.

@@            Coverage Diff             @@
##           master     #728      +/-   ##
==========================================
+ Coverage   78.77%   80.67%   +1.89%     
==========================================
  Files          53       69      +16     
  Lines        4387     6054    +1667     
==========================================
+ Hits         3456     4884    +1428     
- Misses        749      930     +181     
- Partials      182      240      +58     

Impacted Files	Coverage Δ
x/subspaces/types/codec.go	0.00% <0.00%> (ø)
x/subspaces/types/models.go	86.86% <ø> (ø)
x/subspaces/types/msgs.go	97.45% <ø> (ø)
x/subspaces/types/permissions.go	65.38% <ø> (ø)
x/profiles/types/genesis.go	94.73% <50.00%> (ø)
app/app.go	79.82% <52.63%> (-0.79%)	⬇️
x/profiles/legacy/v300/store.go	61.53% <61.53%> (ø)
x/profiles/client/cli/cli_relationships.go	76.04% <73.33%> (+0.53%)	⬆️
x/profiles/keeper/keeper_relationships.go	70.00% <75.00%> (+1.03%)	⬆️
x/subspaces/keeper/alias_functions.go	81.31% <81.31%> (ø)
... and 21 more

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[dadamu]

Overrall is good to me. Just have minor questions as above, and the sim test is failed.

[dadamu]

Ready to go🚀