VOTE-856 update to wysiwyg embedded icon list

[rayestrada]

Update content editing permissions

Jira ticket

https://cm-jira.usa.gov/browse/VOTE-856

Description

Add new function to wysiwyg placeholder to embed an icon from a theme file.

Deployment and testing

Post-deploy

1. run lando retune

QA/Test

1. visit https://vote-gov.lndo.site/node/add/page
2. Click on the "embedded content" button in the wysiwyg and select "Placeholder" from the dropdown
3. Enter "icon:Printer" in the field and submit the dialog
4. Check and see if the icon shows up in the wysiwyg.
5. Save the page and check that it displays correct.

Checklist for the Developer

• A link to the JIRA ticket has been included above.
• No merge conflicts exist with the target branch.
• Automated tests have passed on this PR.
• A reviewer has been designated.
• Deployment and testing steps have been documented above, if applicable.

Checklist for the Peer Reviewers

• The file changes are relevant to the task objective.
• Code is readable and includes appropriate commenting.
• Code standards and best practices are followed.
• QA/Test steps were successfully completed, if applicable.
• Applicable logs are free of errors.

[clmedders]

looks good was able to add icon in the edit view and rendered on page