fix: RekeyTest stability

[kruton]

Use Kotlin StateFlow for rekey count so we do not need to use delay. Provide a way to pass a CoroutineDispatcher to the state machine so it can be on the same clock as the tests. This lets us advance time virtually in a test.

[Copilot]

Pull request overview

Improves the stability of rekey-related tests by making rekey observation deterministic (via StateFlow) and allowing SshConnection’s state machine to run on an injected dispatcher so tests can use the same virtual clock.

Changes:

• Replace FakeSshServer.rekeyCount integer polling/delays with a StateFlow that tests can await.
• Update RekeyTest to use StandardTestDispatcher(testScheduler) and await rekey events rather than sleeping.
• Add stateMachineDispatcher injection to SshConnection and adjust dispatcher lifecycle handling in close().

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 8 comments.

File	Description
sshlib/src/test/kotlin/org/connectbot/sshlib/client/RekeyTest.kt	Removes delay-based polling and switches to awaiting a rekey StateFlow while using a test dispatcher/scheduler.
sshlib/src/test/kotlin/org/connectbot/sshlib/client/FakeSshServer.kt	Exposes rekey count as a StateFlow and allows launching server coroutines on a provided coroutine context.
sshlib/src/main/kotlin/org/connectbot/sshlib/client/SshConnection.kt	Introduces injectable stateMachineDispatcher and changes shutdown behavior around dispatcher closing.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.