Remove sub theme to prevent demo site errors

Remove all sub theme files #42

Unregistered subtheme

Attempt to prevent

Twig\Error\LoaderError: Template "@subtheme_common_design/cd/cd-header/cd-header.html.twig" is not defined in "themes/contrib/common_design/subtheme_common_design/templates/page.html.twig" at line 4. in Twig\Loader\ChainLoader->getCacheKey() (line 142 of /srv/www/vendor/twig/twig/src/Loader/ChainLoader.php). 

related to the Drupal twig namespacing, where registered themes are automatically given themename as namespace. Removing .yml extension from .info file allows the subtheme files to be added to the common_design theme without its templates being active.

Sub theme example

Sub theme example to use for implementations, better READMEs, user menu with dropdowns, page template overrides for 404 and maintenance

Conditional for Component module

to prevent twig errors breaking pages if Component module is not enabled

Improvements to global header and user menu

As described #36

Improvements to base theme

layout and styles for when js is disabled, js polyfills, namespacing and improvements for cd-dropdown, user menu with icon and WIP username display in user menu

Vanilla JS dropdowns, no jquery dependency, components

Removed jquery dependency, replace with vanilla js dropdown
Add components (needs Components module)

📌 Rearrange dependencies!

Move required build tools to the dependencies section. If they remain in devDependencies, they will not be installed when the production container is built with NODE_ENV=production and cause a build failure.

Better icons, focus state, form alter preprocess, namespacing

introducing namespaced svg icons #19
accessibility improvements using focus state #16
undo form alter hook in preprocess once and for all, with code in comments to provide boilerplate code to enable #18
main menu style improvements for active path #17
Corrects declaration of dependencies #15
reduce svg collection to only those included in header or footer
add some basic layout rules, meant as starting points for site-specific layouts
better bem and cd- prefix for layout control

Accessibility improvements and other fixes from ocha_basic

See #9 for details