Multiple required fields on multiple tabs do no trigger frontend validation

Problem/Motivation

Per #2787179: Ensure visibility of invalid fields (JS), it added frontend validation for required fields on multiple tabs. However, if there are multiple tabs with multiple fields you don't get prompted/pushed to the next tab to fill out the required field. Instead, the page will submit, and you'll experience server side validation.

I think this is fine but would appreciate consistency and expect all required tabs to be validated in the fronted.

Steps to reproduce

• Add field groups
• Add three tabs (horizontal)
• Make a required field on each tab
• Try submitting the node outright. You should be prompted to fill out the current tab's required field
• Once the current tab's field is populated, submit again. You should be jumped to the next tab and required field.
• Now that the 2nd required tab has been filled in, submit again. The page will submit and you'll see a server side error

Proposed resolution

Regardless of the number of required tabs, form validation occurs in the front end.

Remaining tasks

User interface changes

API changes

Data model changes