feat(x/nft): add data field in Class type of NFT module (#10501)

## Description

Adds a `data` field in `Class` type of `x/nft`.

Closes: #10494

<!-- Add a description of the changes that this PR introduces and the files that
are the most critical to review. -->

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) 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)

docs/core/proto-docs.md

@@ -7295,6 +7295,7 @@ Class defines the class of the nft type.
 | `description` | [string](#string) |  | description is a brief description of nft classification,optional |
 | `uri` | [string](#string) |  | uri is a URI may point to a JSON file that conforms to the nft classification Metadata JSON Schema.optional |
 | `uri_hash` | [string](#string) |  | uri_hash is a hash of the document pointed to uri,optional |
+| `data` | [google.protobuf.Any](#google.protobuf.Any) |  | data is the metadata of NFT classification,optional |
 
 
 

proto/cosmos/nft/v1beta1/nft.proto

@@ -24,6 +24,9 @@ message Class {
 
   // uri_hash is a hash of the document pointed to uri,optional
   string uri_hash = 6;
+
+  // data is the metadata of NFT classification,optional
+  google.protobuf.Any data = 7;
 }
 
 // NFT defines the NFT.