Fix instances count on main menu

[seadowg]

Closes #6531

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

The biggest change I had to make here was to modify InstancesDataServices so that the instances counts were qualified by project. As part of this, I ended up introducing a more formalized way to create/work with data services in the form of a DataService abstract class (in Data.kt).

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?

The changes made are pretty widespread, so I think a general check of downloading, updating, saving and sending forms would be good here.

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