feat: wi-76 make UI demo optional

[wesleyboar]

Overview

Allow the UI demo to be optional in a full build.

Related

• WI-76

Changes

• added NEEDS_DEMO variable to Makefile and passed it to Docker build command
• changed Dockerfile to run different commands depending on value of NEEDS_DEMO

Testing

1. Core-CMS

1. Build with no UI demo.
   

2. Verify UI demo does not build.

   Details

   You should not see this:

   > @tacc/core-cms@4.1.0 build:ui-demo
   > cd taccsite_ui && fractal build
   
   + Included Core-CMS stylesheets
   /assets/core-styles.cms.css
   /../../static/site_cms/css/build/core-cms.css
   ✔ Build started...
   ⚑ Exported 1 of 552 items
   �[2K�[1A�[2K�[G⚑ Exported 2 of 552 items
   ...
   

3. Build with a UI demo.
   

4. Verify UI demo does build.

   Details

   You should see this:

   > @tacc/core-cms@4.1.0 build:ui-demo
   > cd taccsite_ui && fractal build
   
   + Included Core-CMS stylesheets
   /assets/core-styles.cms.css
   /../../static/site_cms/css/build/core-cms.css
   ✔ Build started...
   ⚑ Exported 1 of 552 items
   �[2K�[1A�[2K�[G⚑ Exported 2 of 552 items
   ...
   

2. Core-CMS-Custom or tup-ui

1. Build CMS with a "no demo" image.
2. Verify http://localhost:8000/static/ui/index.html loads 404.
3. Build CMS with a "has demo" image.
4. Verify http://localhost:8000/static/ui/index.html loads UI demo.

Note: Were you to build again, with build_ui_demo unchecked, a demo would not be built, but would still exist in the image, because Docker would use cached layer, because no files were changed.

UI

w/ Demo	no Demo

[jarosenb]

LGTM

[taoteg]

LGTM.