Created a ChartsInterface as a place to define constants. Also moved the API example module into the modules folder. And fixed code formatting in some places.

Responding to issue 2869541: Only display libraries that are enabled as options in the Charting Library options field.

Add an example module for people wanting to understand how to use the Charts module without making use of Views. Also fixes small issue with X-axis title in Highcharts.

This commit takes all sub-module-specific code out of the core charts module, making the module more extensible. It also improves the libraries.yml files and removes unused code from various parts of the site.

add default configuration form to Config page, fix the link to add a new view, and minor pareview fixes, particularly short syntax for arrays

Charts can accept 'create secondary y-axis' option from Chart Attachment displays. This commit also removes a bug in Charts Google that led to duplicate empty fields.

Issue #2202425 by bryanlburkholder and quicksketch: Support for window resizing event in Google Charts.

This reverts commit 31a47799.