feat(examples): grc20 refactor

[moul]

This PR extracts the grc20 refactor from #2551, which is a meta PR containing several contract improvements and additions that depend on new Gnovm features that haven't been merged yet.

Please review this grc20 refactor with a focus on its API. Several valuable comments can be found in #2551. Additionally, you can discover new contracts using grc20 in #2551, such as minidex, atomicswap, grc20reg, test20, and vault.

Addresses #1832

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.76%. Comparing base (60304df) to head (b40f6fb).
Report is 2 commits behind head on master.

Additional details and impacted files

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##           master    #2983   +/-   ##
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  Coverage   63.76%   63.76%           
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  Files         548      548           
  Lines       78681    78681           
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+ Hits        50171    50172    +1     
- Misses      25128    25129    +1     
+ Partials     3382     3380    -2     

Flag	Coverage Δ
contribs/gnodev	61.16% <ø> (ø)
contribs/gnofaucet	14.82% <ø> (ø)
gno.land	73.62% <ø> (ø)
gnovm	67.92% <ø> (ø)
tm2	62.41% <ø> (-0.01%)	⬇️

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[leohhhn]

cc @MikaelVallenet @n0izn0iz, any thoughts?

[MikaelVallenet]

cc @MikaelVallenet @n0izn0iz, any thoughts?

looks good to me, i like the teller pattern & add metadata in token level instead of ledger/bank
i'm just thinking if it should take another pkg as an extension of primitive grc20 pkg

[thehowl]

Still mostly naming considerations.

[moul]

Merged #3046 over this one to make the CI green.

Depends on #3046.

[thehowl]

Overall implementation and naming LGTM.

[n0izn0iz]

I think this PR should also update the docs

• https://docs.gno.land/concepts/effective-gno#grc20-tokens
• https://docs.gno.land/how-to-guides/creating-grc20

[moul]

@leohhhn do you want to update the doc in this PR or in your big refactor?

[leohhhn]

LGTM; I feel like showcases and more examples will come after we merge this PR.

I'll also port my constant product dex example afterwards.

As for the doc, I can push changes to your branch here to update it, or make a PR when we merge this. Let me know how you want to go about it.