ECharts: support tree shaking

[vhdirk]

Description

As mentioned in #1933, the user currently has make the echarts library globally available. This PR provides a way to resolve that and enable full tree-shaking support. This should also be a partial fix for #1775.

What's included?

This PR introduces a new TD_ECHARTS_CONFIG injectiontoken that is used to pass the echarts library reference to CovalentBaseEchartsModule.

import * as echartsLibraryReference from 'echarts';

...
  CovalentBaseEchartsModule.forRoot({
    echarts: echartsLibraryReference,
    defaultThemes: false
  }),

or  

providers: [{
  provide: TD_ECHARTS_CONFIG,
  useValue: {
    echarts: echartsLibraryReference,
    defaultThemes: false
  }
}]

Test Steps

• npm run start
• then this
• finally this

General Tests for Every PR

• npm run start still works.
• npm run lint passes.
• npm run stylelint passes.
• npm test passes and code coverage is not lower.
• npm run build still works.

Screenshots or link to StackBlitz/Plunker

[owilliams320]

@vhdirk Can you seperate out the schematic and a11y additions if that is not related to echarts?

[owilliams320]

@vhdirk looks like the tests and e2e job is failing can you fix this?

[vhdirk]

@owilliams320 unfortunately, I'm having some time of for personal reasons. I won't be able to work on this for a while.

[vhdirk]

@owilliams320 unfortunately, I'm having some time of for personal reasons. I won't be able to work on this for a while.

[owilliams320]

Sure no problem. We will close this and come back to it when you have time