feat: Icon update

[fsbraun]

Description

This PR updates the icon library for a more consistent user experience. It provides icon styles in a new css file cms.icons.css which can be used by other packages to allow for a uniform icon set.

Icon naming now consistently follows the rule cms-icon-<function>.

Historically, some icons were named after their content (e.g., cms-icon-cogs). Those icons remain available for the moment but are deprecated. Use the new icons instead: cms-icon-advanced-settings.

The pencil icon was used for settings and edit. Now it is deprecated and there are new icons for edit, edit-new, and settings.

Also, icons of some core packages are included:

• djangocms-versioning
• djangocms-alias
• djangocms-moderation
• djangocms-version-locking.

Here's a preview of the new "look and feel":

New icons:

• advanced-settings:
• alias:
• apphook:
• archive:
• comment:
• cut:
• edit:
• edit-new:
• manage-versions:
• moderate: (thanks to @svandeneertwegh !)
• publish:
• redo:
• rename:
• settings:
• undo:
• unlock:
• unpublish:
• view:

Included but deprecated

These icons describe content not functionality and are deprecated.

• cogs
• eye
• layers
• pencil
• scissors
• puzzle

Checklist

• I have opened this pull request against develop-4
• I have added or modified the tests when changing logic
• I have followed the conventional commits guidelines to add meaningful information into the changelog
• I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.