Merge branch 'add-dataset-dropdown' into 'master'

src/app/api.service.ts

src/app/app.module.ts

...p/components/select-dataset/select-dataset.component.html

...p/components/select-dataset/select-dataset.component.scss

...omponents/select-dataset/select-dataset.component.spec.ts

...app/components/select-dataset/select-dataset.component.ts

src/app/pages/explorer-page/explorer-page.component.html

src/app/pages/explorer-page/explorer-page.component.ts

src/app/pages/protein-network.ts

src/assets/positions/network-KroganSARS-CoV2.json

src/assets/positions/network-TUMHCoV.json

...positions/network-TUMHCoVTUMSARS-CoV2KroganSARS-CoV2.json

src/assets/positions/network-TUMSARS-CoV2.json

...assets/positions/network-TUMSARS-CoV2KroganSARS-CoV2.json

src/assets/positions/network.json