Merge branch '102-delete-stale-files' into 'main'

...oject/mailbox/core/system/AndroidTaskSchedulerModule.java

...java/org/briarproject/mailbox/core/CoreEagerSingletons.kt

...src/main/java/org/briarproject/mailbox/core/CoreModule.kt

...n/java/org/briarproject/mailbox/core/files/FileManager.kt

...in/java/org/briarproject/mailbox/core/files/FileModule.kt

...rproject/mailbox/core/files/StaleFileDeletionScheduler.kt

...ava/org/briarproject/mailbox/core/system/TaskScheduler.kt

...src/test/java/org/briarproject/mailbox/core/TestModule.kt

...rproject/mailbox/core/files/FileManagerIntegrationTest.kt

...iarproject/mailbox/core/system/TestTaskSchedulerModule.kt