Add Google OAuth login option for header component login

[spwoodcock]

Is your feature request related to a problem? Please describe.

• DroneTM needs login - Google OAuth is a good start.

Describe the solution you'd like

• Add login options to header component.
• One option should be full OAuth flow for Google login.

Additional context

• Should be designed so we can add other login methods easily too.

[emi420]

Why Google first? we're using OSM login for most of our tools.

[spwoodcock]

For Drone TM 👍
(our existing tools are OSM-centric, but FMTM and Drone TM need flows outside of OSM. DroneTM actually has nothing to do with OSM)

We have oauth flows already developed for OSM, so that's easy to add.

Drone TM also already has Google Oauth in place, so I'm sure you can copy code from there!