[meta] Self-assess the Webform module for Drupal 8's accessibility

Problem/Motivation

The Webform module and Drupal aim to be fully accessible to all. Stating that a piece of software is accessible, does not prove that it is accessible. We should quantitate the Webform module's accessibility as well as provide a benchmark for tracking the Webform module's ongoing accessibility

Proposed resolution

Self-assess the Webform module for Drupal 8's accessibility using Berkeley's Web Access Do-It-Yourself (DIY) Accessibility for Developers Google Sheet.
https://webaccess.berkeley.edu/evaluating/self-assessment/diy-accessibil...

Here is the Webform module for Drupal 8: DIY Accessibility for Developers

Remaining tasks

• Copy and shared spreadsheet
• Review WCAG
• Review Code
• Review Keyboard
• Review Automated
• Review Real people
• Create needed tickets for issues
• Remediate issues
• Document results (Blog post on jrockowitz.com and https://opencollective.com/webform)
• Add self-assessment callout to Webform project page

User interface changes

Some issues might require UI tweaks.

API changes

N/A

Data model changes

N/A

Release notes snippet

TBD (Most likely a blog post and callout.)