Warn if running plugin from source

[swissspidy]

Summary

Warn users if they forgot to run the build commands.

Helpful if someone just downloads the current master branch as a ZIP file and expects the plugin to "just work".

Relevant Technical Choices

Uses an anonymous function because this cannot really be covered by unit tests and this shouldn't be disabled by others.

To-do

User-facing changes

Testing Instructions

Download the master branch and try to install the plugin on a fresh install, or simply remove the vendor folder to force the admin notice from appearing.

---

Fixes #1234
See #2961

[codecov]

Codecov Report

Merging #2962 into master will increase coverage by 0.80%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2962      +/-   ##
==========================================
+ Coverage   81.22%   82.02%   +0.80%     
==========================================
  Files         714      718       +4     
  Lines       12016    12068      +52     
==========================================
+ Hits         9760     9899     +139     
+ Misses       2256     2169      -87     

Flag	Coverage Δ
#karmatests	63.50% <ø> (+3.88%)	⬆️
#unittests	66.58% <ø> (+0.02%)	⬆️

Impacted Files	Coverage Δ
.../app/views/editorSettings/googleAnalytics/index.js	25.00% <0.00%> (-25.00%)	⬇️
assets/src/edit-story/app/font/fontProvider.js	60.00% <0.00%> (-2.50%)	⬇️
assets/src/dashboard/app/api/apiProvider.js	100.00% <0.00%> (ø)
assets/src/edit-story/app/media/mediaProvider.js	100.00% <0.00%> (ø)
assets/src/edit-story/app/media/useMediaReducer.js	100.00% <0.00%> (ø)
...ts/src/dashboard/app/views/editorSettings/index.js	0.00% <0.00%> (ø)
...s/src/edit-story/app/media/utils/createResource.js	100.00% <0.00%> (ø)
...c/dashboard/app/views/editorSettings/components.js	57.14% <0.00%> (ø)
...p/media/media3p/useProviderContextValueProvider.js	100.00% <0.00%> (ø)
...c/dashboard/storybookUtils/formattedUsersObject.js
... and 34 more

[github-actions]

Size Change: -1.26 kB (0%)

Total Size: 1 MB

Filename	Size	Change
assets/js/edit-story.js	458 kB	+252 B (0%)
assets/js/stories-dashboard.js	526 kB	-1.52 kB (0%)

ℹ️ View Unchanged

Filename	Size	Change
assets/css/edit-story.css	269 B	0 B
assets/css/stories-dashboard.css	305 B	0 B
assets/css/web-stories-embed-block.css	515 B	0 B
assets/js/web-stories-embed-block.js	15.7 kB	0 B

_{compressed-size-action}

[spacedmonkey]

Did you consider using wp_die? It maybe over kill, but it is something to consider.

[swissspidy]

wp_die is quite drastic - we don't want the site from working :-)

[spacedmonkey]

👍

[spacedmonkey]

👍

[spacedmonkey]

@swissspidy This is good to go!