Fix autosend scheduling

[seadowg]

Closes #6120

This also:

• Fixes problems introduced recently where form level auto send was no longer working
• Makes sure that pending auto send jobs will run after an app upgrade (even if there is a change in the underlying code)
• Will not run "Cellular only" auto send when connected to a metered wifi (like a hotspot), but will retry later (with an exponential back off)

It's probably a good idea to wait on merging this until it's marked "behaviour verified" as we've seen a lot of churn on auto send recently.

Why is this the best possible solution? Were any other approaches considered?

I would have loved to have a more elegant solution for "cellular only", but couldn't find one that would work within the WorkManager world. I think the compromise of having other settings work optimally within Android's current background job setup is correct though.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

This should mean that auto send now behaves more like how we'd "expect". One caveat to highlight is that metered wifi (like a hotspot) will not work with "wifi only" or "cellular only". The work around for this (other than using "wifi or cellular") is to change the wifi to "unmetered" in Android's settings.

Before submitting this PR, please make sure you have:

• [x] added or modified tests for any new or changed behavior
• [x] run ./gradlew connectedAndroidTest (or ./gradlew testLab) and confirmed all checks still pass
• [x] added a comment above any new strings describing it for translators
• [x] verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• [x] verified that any new UI elements use theme colors. UI Components Style guidelines

[seadowg]

@WKobus could you take another look at this when you get a chance? The biggest change since you last looked is that "cellular only" shouldn't run when connected to a metered wifi (like a hotspot), but should run eventually if you then just connect to cellular (although it might take a few minutes).