feat: handle session expiration [LIBS-169]

[amcgee]

Implement a user workflow in App Platform to handle session expiration and allow the user to re-authenticate

This is a work-in-progress, I've based it on #748 for now but will update target to master once that has been merged

Requires dhis2/app-runtime#1266
Requires dhis2/ui#1161

TODO

• Styling improvements @cooper-joe
• Modal height issue
• Actually check for auth status (Required app-runtime change)
• Make permanent AlertBar non-dismissable (Requires ui change)
• Better error handling
• Test with different login configurations
• Consider opening login page with _blank target instead of modal
• Consider implementing proper login API
• Check functionality under different network conditions
• Use experimental d2.config flag
• Support logout?

From Struts-based login.vm

• OIDC provider login
• Use messages from system config
• Password recovery?