Fixed: custom HTML widget not rendering on published portals

[malincrist]

Problem

After updating to the new model registration, the custom HTML widget was registered with the wrong name for publishing. This results in the widget not being rendered for published portals.

Solution

Register custom HTML widget with the correct name.

Closes #2369

[github-actions]

Accessibility Insights Action: All applicable checks passed

• URLs: 13 URL(s) passed, and 0 were not scannable
• Rules: 29 check(s) passed, and 23 were not applicable
• Download the Accessibility Insights artifact to view the detailed results of these checks

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This scan used axe-core 4.3.2 with Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36.