Use Highcharts fork with temporary .flat prop fix for missing plotline label

[cfarm]

This PR updates cfpb-chart-builder to temporarily use a fork of Highcharts. The fork fixes a conflicting .flat JS property which caused missing plotline labels (the projected data label) on all the charts that have projected data.

The bug is in Chrome 69 and Firefox 62, in older versions of Highcharts. See this issue with description of the bug: highcharts/highcharts#8477

Here is the bug fix, from Highcharts v6.1.2: highcharts/highcharts@83b5d31

We had to backport this bug fix to an older version of Highcharts so we can launch with cfpb-chart-builder on Highcharts v5.0.11. We will upgrade to v6 post-launch ASAP but we anticipate major CSS development to get the charts working in our supported browsers and styled to match our designs, hence this PR.

Read the "Notes" below for a detailed description of how the forked Highcharts package was created.

Additions

Removals

Changes

• uses CFPB fork of highcharts-dist repo in place of highcharts npm package
• the forked branch fix-missing-plotline-label includes the backported bug fix

Testing

• ./setup.sh
• gulp watch
• go to http://localhost:5000/ and verify the "Values after ___ are projected" labels are visible on Origination activity, bar charts, and inquiry index charts

Screenshots

Notes

more detailed description TBA, for now here were the steps i took. i'll add more context on why:

1. fix in cfarm/highcharts source
2. compile the JS in the same cfarm/highcharts repo:
   • npm install
   • gulp scripts --file highcharts.src.js,highmaps.src.js,highstock.src.js,modules/stock.src.js
3. copy these files from the highcharts/code folder to github cfarm/highcharts-dist (overwriting existing files):
   • highcharts.src.js
   • highmaps.src.js
   • highstock.src.js
   • modules/stock.src.js
   • js/highcharts.src.js
   • js/highmaps.src.js
   • js/highstock.src.js
   • js/modules/stock.src.js
4. minify the above files in highcharts-dist:
   • use https://closure-compiler.appspot.com/home for each file (this is akin to highcharts' own minification process)
   • save each file as .js extension (without .src)
5. fork the fix in cfpb/highcharts and cfpb/highcharts-dist instead of cfarm

Todos

• test in all supported browsers with Sauce

Checklist

• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows the standards laid out in the front end playbook
• Passes all existing automated tests
• New functions include new tests
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged
• Visually tested in supported browsers and devices
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)

[cfarm]

y'all don't let me merge this without testing in all supported browswers

[anselmbradford]

Tested in latest Chrome, FF, Safari, and Opera. Does not work in IE, but this is a different issue https://[GHE]/CFGOV/platform/issues/3025