feat(tauricon): remove from cli

[nothingismagick]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

This PR removes the tauri icon command from the CLI, it can be found at https://github.com/tauri-apps/tauricon

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

Tests pass locally with tauri icon removed, and in the new repo as well.

[lucasfernog]

We're moving the icon command to a dedicated CLI: https://github.com/tauri-apps/tauricon