feat: initialize module x/nft

[chengwenxi]

Summary

Implements ADR-043-nft.

A generic module to store NFTs based on discussion #9065 and PR #9329.

1. x/nft only stores NFTs by id and owner. NFT contains a data field as a proto.Any.
2. The data field CAN be used by composing modules to specify additional properties for the NFT to support their own use cases, such as ERC721 transferred from Ethereum through the Gravity bridge.

[tac0turtle]

Thank you for opening this PR. I would love to see this be the first item that goes through the newly established CIP process since it may live on the hub. @ebuchman what do you think?

(https://github.com/cosmos/cips)

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[orijbot]

Visit https://dashboard.github.orijtech.com?pr=9174&repo=cosmos%2Fcosmos-sdk to see benchmark details.

[okwme]

Looks like there are some linting errors that came up from golangci-lint:

 Running [/home/runner/golangci-lint-1.39.0-linux-amd64/golangci-lint run --out-format=github-actions --timeout 10m] in [] ...
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `Id` should be `ID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)
  Error: struct field `ClassId` should be `ClassID` (golint)

[aaronc]

Can we please have this broken up into smaller PRs? It is really hard to do good reviews of such large pieces of work all at once.

I would suggest individual PRs roughly in this order:

• just the .proto files
• just the MsgServer implementation and corresponding keeper methods
• just the QueryServer implementation and corresponding keeper methods
• CLI
• simulations

[chengwenxi]

Can we please have this broken up into smaller PRs? It is really hard to do good reviews of such large pieces of work all at once.

Good suggestion, We will split into several PRs to this branch(vincent/nft).

• Proto files, feat: generate nft protobuf #9747
• MsgServer implementation and corresponding keeper methods
• QueryServer implementation and corresponding keeper methods
• CLI
• Simulations

[aaronc]

Can we please have this broken up into smaller PRs? It is really hard to do good reviews of such large pieces of work all at once.

Good suggestion, We will split into several PRs to this branch(vincent/nft).

• Proto files, feat: generate nft protobuf #9747
• MsgServer implementation and corresponding keeper methods
• QueryServer implementation and corresponding keeper methods
• CLI
• Simulations

Thanks! Please make PRs against master if you want the SDK team to review.

[chengwenxi]

I created issue #9826 to track the nft related PRs, so I closed it.