Survey QR code reader right in the App

[jo-spek]

Reading the QR code to join a survey currently requires a different app (usually camera app, but on a lot of older devices, people still have to install a separate app, which is often some bloaty trash app).

Occasionally, it also creates problems, because Ground is then started within that other app.

Ideally, we would have a "Join a survey" button in the survey overview, from where the survey QR code can be read right from Ground itself.

Could look something like this:

[jo-spek]

Just testing Ground in Cameroon, and the lack of a QR code reader right in the app is a major obstacle. Around 70% of participants at a workshop with 100 people could not scan the QR code with their camera apps, but would need to download some bloaty QR code reader app.

Upping it to P1, but I'd even argue for P0.

@kenstershiro @gino-m @andreia-ferreira @shobhitagarwal1612

[kenstershiro]

The request makes sense and it looks like it shouldn't be too complex to implement, esp if we use the Google Code scanner, but will defer to @andreia-ferreira and @shobhitagarwal1612 for that part. Adding @vittorino if you have any capacity to sketch out a UI for the call to action for this. Added as a candidate for next iteration.