Issue with using snapstate Active for interface repository

[pedronis]

@pedronis

One issue here is that the atomicity of setup-profiles , which does release the state lock and might touch more than one snap profiles, and also of other tasks/ops of ifacestate manager, is guaranteed through a simple blocked predicate set on the ifacestate manager TaskRunner. This breaks down if part of those tasks are executed instead under tasks of the snapstate manager and its runner, and needs a solution.

a relatively simple solution but needing some work is to migrate to have just one shared TaskRunner, needs some double checking and care, but I think the mostly affected area will be tests that will need a bit of changes, some test patterns will need to change.

Some of the ideas under Cross-snap operations, bases, and concurrency would be easier in a world with a single shared TaskRunner as well.