Implement improvements to APG support tables

[ccanash]

Implement proposed improvements to APG support table https://github.com/w3c/aria-at-app/issues/964 .

A table with one row for every browser/AT combination, one column for Must, and one column for Should, where each cell is the percentage of passing tests in that intersection.

If there is no must or should assertion we would display: Not applicable.

[ccanash]

Feedback received during APG Task Force meeting:

• [x] 1. Rename the columns to "Must Have Behaviors" and "Should Have Behaviors" so there is consistency between the aria-at-app report page to which the iframe links, and because "must have" is easier to understand language.
• [x] 2. Sort the rows alphabetically by AT first, then Browser -- so JAWS + Chrome, JAWS + Firefox, ... NVDA + Chrome, ..., etc.

Feedback from the ARIA-AT Community Group Meeting:

• [x] 1. Add a column title for the first column of "Assistive Technology - Browser"
• [x] 2. Remove the word "Supported" from each cell.
• [x] 3. Make each row have a smaller height by putting the number and graphic on the same line.
• [x] 4. P2 requirement that could implemented in a later PR: Make each AT-Browser row title into a link that takes the user to the detail report page for that combination, e.g., JAWS and Chrome for Radio Group Example Using aria-activedescendant | ARIA-AT Reports