feat: Create x/curation module data model and tx API

[aaronc]

ref: #374

I had some ideas in my head on this so wanted to get them down. This proposes an API for the x/curation module as proposed in #374.

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[codecov]

Codecov Report

Merging #395 (d7d2802) into master (6f3b83b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #395   +/-   ##
=======================================
  Coverage   61.01%   61.01%           
=======================================
  Files          51       51           
  Lines        3317     3317           
=======================================
  Hits         2024     2024           
  Misses       1029     1029           
  Partials      264      264           

Flag	Coverage Δ
experimental-codecov	61.01% <ø> (ø)
stable-codecov	61.01% <ø> (ø)

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[ruhatch]

Looks like a reasonable API to me.

Do we want to be able to delete a tag/tagset as well?

Also a quick question on naming - some places the messages are name with Request and some places they're not. Do we have a consistent guideline for that?

[aaronc]

Do we want to be able to delete a tag/tagset as well?

Likely not, I think.

Also a quick question on naming - some places the messages are name with Request and some places they're not. Do we have a consistent guideline for that?

Remove Request is now the convention.

[blushi]

what if we only want to edit one field (eg name)? Should we just have the rest of the fields set with their current values?

[aaronc]

Closed in favor of #609