arcgis username and password authentication

[Skosche3]

Provides draft for peer review for adding username/password authentication with ArcGIS server.

Things to possibly do yet

1. Update UI webapp to provide username/password options or token with url, remove hardcoded section for testing
2. Testing and handle use cases beyond happy path
3. Move getServerUrl to Helper file
4. Move getPortalUrl to Helper file
5. Update layer token to get token from identity manager
6. Move plugins/arcgis/web-app/projects/main/src/lib/arc-layer/arc-layer.component.ts addLayer to helper file and use instead of encodeURIComponent
7. Provide ability to refresh token upon expiration (if needed)
8. Any remaining TODOs

[newmanw]

Couple comments here we can look at as we proceed, nothing holding up this PR>

[ryanslatten]

Looks like you have some merge errors