Close #582, implement 2-column Story Tables with no trigger var

In this PR, I have:

[x] Added tests for any new features or bug fixes (if relevant)
[x] Added my changes to the CHANGELOG.md at the top, under the "Unreleased" section
[x] Ensured issues that this PR closes will be automatically closed

Reason for this PR

Allow authors to avoid proxy variables and their complications in Story Tables. This means a 2-column layout where the var column never contains x, i, etc, just the name of the actual variable that needs to be set.

It does require the author to put new HTML in their interview:

<div id="alkiln_proxy_var_values"
      data-generic_object="${ encode_name(str( x.instanceName if defined('x') else '' )) }"
      % for letter in [ 'i', 'j', 'k', 'l', 'm', 'n' ]:
      data-index_var_${ letter }="${ encode_name(str( value( letter ) if defined( letter ) else '' )) }"
      % endfor
      aria-hidden="true" style="display: none;"></div>

Links to any solved or related issues

Closes #582 - 2 column table Closes #573 for now, shortening the message a little. We'll work more on error messages another time. Closes #452 for now. Reduces the number of times we show this error message.

Also:

Add name of Scenario to progress dots. May help with logging progress on GitHub
Add internal test should fail even when the report is correct (a previously undiscovered bug)
Allow "expected status" tests to accept more than 'passed' and 'failed'
Added doc explaining what results we expect
Fix failures because upstream Assembly Line change added punctuation

Any manual testing I have done to ensure my PR is working

None on the final product

SuffolkLITLab / ALKiln