feat(tokens): export json, remove duplicate file generation

[castastrophe]

Description

Add JSON to token package exports.

Remove CSS files from commit history (but continue to build and ship them in the releases).

Stop physically copying the dist/css/index.css to dist/index.css and instead, map dist/index.css in the package exports to the same dist/css/index.css file.

How and where has this been tested?

Please tag yourself on the tests you've marked complete to confirm the tests have been run by someone other than the author.

Validation steps

Expect to see the bundled index.css files for the tokens dist output not reflected in diffs for a pull request. Expect the files to continue to be generated.

• Alter the @adobe/spectrum-tokens package version being used by tokens.
• Run yarn builder tokens --skip-nx-cache. Do not commit the changes.
• Expect not to see the index.css asset listed in the files staged or unstaged for commit.
• Expect to see changes reflected in the *-vars.css and the tokens.json resource.
• Expect to see changes reflected when you run yarn compare tokens.

To-do list

• I have read the contribution guidelines.
• I have updated relevant storybook stories and templates.
• I have tested these changes in Windows High Contrast mode.
• If my change impacts other components, I have tested to make sure they don't break.
• If my change impacts documentation, I have updated the documentation accordingly.
• ✨ This pull request is ready to merge. ✨

[changeset-bot]

🦋 Changeset detected

Latest commit: cb797cb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@spectrum-css/tokens	Minor
@spectrum-css/preview	Patch

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[github-actions]

🚀 Deployed on https://pr-3529--spectrum-css.netlify.app

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File metrics

Summary

Total size: 3.25 MB^*
Total change (Δ): 🟢 ⬇ 201.77 KB (-5.72%)

Table reports on changes to a package's main file. Other changes can be found in the collapsed Details section below.

Package	Size	Δ
tokens	🚨 deleted/moved	🟢 ⬇ 201.95 KB

Details

tokens

Filename	Head	Compared to base
css/dark-vars.css	48.04 KB	🔴 ⬆ 0.04 KB (0.07%)
css/global-vars.css	44.20 KB	🔴 ⬆ 0.04 KB (0.08%)
css/index.css	201.96 KB	🔴 ⬆ 0.01 KB (0.00%)
css/large-vars.css	32.08 KB	🔴 ⬆ 0.04 KB (0.11%)
css/light-vars.css	48.00 KB	🔴 ⬆ 0.04 KB (0.07%)
css/medium-vars.css	32.24 KB	🔴 ⬆ 0.04 KB (0.11%)
json/tokens.json	289.94 KB	-
index.css	🚨 deleted/moved	⬇ 201.95 KB

* Size determined by adding together the size of the main file for all packages in the library.
* Results are not gzipped or minified.
* An ASCII character in UTF-8 is 8 bits or 1 byte.