Update slash icon, update from XD, and and rename a few tokens

[fredvisser]

Pull Request

🤨 Rationale

1. Replaces temporary forward-slash icon with proper icon
2. Replaces Enterprise green with ForestGreen
3. Replaces Selection100 with DigitalGreenLight
4. Replaces Banner_Fail_100_DarkUI_ with Banner_Fail_100_DarkUI
5. Adds DigitalGreenDark, PowerGreen, and Black22
6. Rename fillColorSelected to fillSelectedColor to match token naming schema.
7. Rename fill-selected-hover-color to fill-hover-selected-color to match token naming schema.

👩‍💻 Implementation

Followed CONTRIBUTING docs to import new icon.
Used XD plugin to import latest Nimble_Components doc

🧪 Testing

Local builds and Storybook review

✅ Checklist

• I have updated the project documentation to reflect my changes or determined no changes are needed.

[msmithNI]

I did the remaining steps for uptaking the token value changes (steps 1-8 of the nimble-tokens contributing doc) in this commit, if you want to pull that change into this PR.

(Currently this PR doesn't have the token renames in the token TS/CSS/CS files)

[atmgrifter00]

Would it be good to change fillColorSelected to fillSelectedColor as part of this PR, since it's already a major version change?

[jattasNI]

I think it would be good to pull in the commit that @msmithNI mentioned so that the token renames propagate all the way through to nimble-components.