Update rx-coroutines interop lint message

[serge-slack]

Summary

Update rx-coroutines interop lint message to:

rxSingle defaults to Dispatchers.Default. Provide an explicit dispatcher which can be replaced with a test dispatcher to make your tests more deterministic.

As Dispatchers.Unconfined may lead to unintended threading and should only be used deliberately, remove it as a recommendation from the lint message.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

The following point can be removed after setting up CI (such as Travis) with coverage reports (such as Codecov)

• I've written tests to cover the new code and functionality included in this PR.

The following point can be removed after setting up a CLA reporting tool such as cla-assistant.io

• I've read, agree to, and signed the Contributor License Agreement (CLA).

[ZacSweers]

Can we meet in the middle? I think the context is helpful

rxCompletable defaults to Dispatchers.Default, which will silently introduce multithreading. Provide an explicit dispatcher.

[serge-slack]

@ZacSweers, how about:

rxCompletable defaults to Dispatchers.Default. Provide an explicit dispatcher.

While it's true that providing no dispatcher can silently can introduce multithreading, imo it also makes the default dispatcher sound less desirable even when used explicitly.

[ZacSweers]

Let's provide some degree of context why, lint checks should educate as much as they can while guardrailing :)

[serge-slack]

Let's provide some degree of context why, lint checks should educate as much as they can while guardrailing :)

In that case I would rather mention that providing an explicit dispatcher aids in testing.

[ZacSweers]

Sure 👍