Add higher level descriptions form in Alt-Text

[JakeWags]

Does this PR close any open issues?

Closes #274

Give a longer description of what this PR addresses and why it's needed

This PR adds a form accordion to the alt-text sidebar which lets the user input meta data (description, set description, item description) which is used by the alt-text generator.

This is saved as a part of the UpSet config and the provenance. Trrack stores the meta data in the provenance history.

In the state export, the metadata is stored in an object like this:

{
"metaData": {
    "description": "An UpSet 2 Plot",
    "sets": "sets",
    "items": "items"
  },
...
}

Provide pictures/videos of the behavior before and after these changes (optional)

Are there any additional TODOs before this PR is ready to go?

TODOs:

• [ ] ...

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[JakeWags]

Better example data:

• set the example to Movies, Movie genres, movie etc

Add a generated sentence as an example for what the fields are used for

Potentially:

• Add a message on dataset load (or alt text sidebar open) if the extra information hasn't been filled out

[JakeWags]

Change trrack description to "Update plot information"