[feature] Update to ECMAScript Modules

[ChazUK]

Is your feature request related to a problem? Please describe.
Trying to build a clientlib containing @adobe/aem-spa-page-model-manager produces this error message.

Warning: /Users/uut1/repos/europe-design-system.webapp/apps/eds-aem-clientlib/src/app/components/model-manager.service.ts depends on '@adobe/aem-spa-page-model-manager'. CommonJS or AMD dependencies can cause optimization bailouts.
For more info see: https://angular.io/guide/build#configuring-commonjs-dependencies

Describe the solution you'd like
@adobe/aem-spa-page-model-manager is compiled to an ECMAScript Module instead of CommonJS so code can be optimised.