Charts support for patterns

[dlabrecq]

In order to better support a11y / color contrast issues, we would like charts to support patterns. See the design issue here:
patternfly/patternfly-org#4369

Patterns shall be dynamically generated (unique for each chart) in order to apply colors from the selected color theme or custom color scale. Those generated patterns will be applied in a specific order (via a URL), similar to the color theme ordering defined by PatternFly. If you were to use the multi-color theme; for example, colorized patterns would be displayed in that same order. However, devs should be able to create their own custom patterns as well.