3.0.0-beta.0: feat(*): update to angular 9/10 and @types/googlemaps

 - switch to @types/googlemaps typing
 - switch to angular building
 - updates to tslint
 - switch from js-marker-clusterer to @google/markerclustererplus
 - general cleanup of unused files
 - update netlify config
 - fix DataLayer `style` type
special thanks to @terencehonles for his work on switching types