Add specific crash message for OOMs

[seadowg]

Closes #6859

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

As discussed in the issue, this doesn't actually fix the crash, but does add a new specific crash message when the app crashes due to an OutOfMemoryError. This won't catch every out of memory problem (as it can result in a range of side effect exceptions), but it should improve the error flow for a lot fo them.

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?

Nothing to test here - good for a reviewer to try and validate this by hacking an OOM into the app.

Before submitting this PR, please make sure you have:

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

[grzesiek2010]

If decode fails, getCrash returns null while hasCrashed() stays true, so KEY_CRASH is never cleared and the app bounces to the crash screen on every launch.

[seadowg]

Good catch! I've convert hasCrashed to an extension (that just uses the getCrash value) to prevent that.