[Forms, ImportFromJSONAction plugin] display form error inside form

[johnriedel]

Closes #7985

Describe your changes:

This feature adds an error message option for every form control created via the Forms API. Error message display is initiated via a form control's validate function. The function's second parameter is a function through which an error message may be passed. For example:

function validate(data, fail) { return fail("My error message."); }

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Is this a notable change that will require a special callout in the release notes? For example, will this break compatibility with existing APIs or projects that consume these plugins?

Author Checklist

• Changes address original issue?
• Tests included and/or updated with changes?
• Has this been smoke tested?
• Have you associated this PR with a type: label? Note: this is not necessarily the same as the original issue.
• Have you associated a milestone with this PR? Note: leave blank if unsure.
• Testing instructions included in associated issue OR is this a dependency/testcase change?

Reviewer Checklist

• Changes appear to address issue?
• Reviewer has tested changes by following the provided instructions?
• Changes appear not to be breaking changes?
• Appropriate automated tests included?
• Code style and in-line documentation are appropriate?

Testing Instructions

1. In the action menu, click "Import From JSON"
2. For the file input, select a non-JSON text file.
3. Upon failed validation, the associated error message will appear in the form under the control.
   

[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 57.27%. Comparing base (5be103e) to head (5530815).

Files with missing lines	Patch %	Lines
src/api/forms/components/FormRow.vue	25.00%	3 Missing ⚠️
...ugins/importFromJSONAction/ImportFromJSONAction.js	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7986      +/-   ##
==========================================
- Coverage   57.70%   57.27%   -0.43%     
==========================================
  Files         678      678              
  Lines       27428    27431       +3     
  Branches     2691     2691              
==========================================
- Hits        15826    15712     -114     
- Misses      11264    11378     +114     
- Partials      338      341       +3     

Flag	Coverage Δ
e2e-ci	62.82% <0.00%> (ø)
e2e-full	23.65% <0.00%> (-18.36%)	⬇️
unit	49.33% <20.00%> (-0.19%)	⬇️

Files with missing lines	Coverage Δ
...ugins/importFromJSONAction/ImportFromJSONAction.js	76.00% <0.00%> (ø)
src/api/forms/components/FormRow.vue	72.97% <25.00%> (-3.50%)	⬇️

... and 15 files with indirect coverage changes

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