Add module mailbox-lib for using mailbox as a library

build.gradle

gradle/variables.gradle

mailbox-android/build.gradle

...c/main/java/org/briarproject/mailbox/android/AppModule.kt

...n/java/org/briarproject/mailbox/android/MailboxService.kt

...g/briarproject/mailbox/android/ui/WipeCompleteFragment.kt

mailbox-cli/build.gradle

...c/main/java/org/briarproject/mailbox/cli/JavaCliModule.kt

...ox-cli/src/main/java/org/briarproject/mailbox/cli/Main.kt

mailbox-core/build.gradle

...iarproject/mailbox/core/lifecycle/LifecycleManagerImpl.kt

...ain/java/org/briarproject/mailbox/core/system/System.java

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

mailbox-lib/.gitignore

mailbox-lib/build.gradle

...a/org/briarproject/mailbox/core/JavaLibEagerSingletons.kt

.../briarproject/mailbox/core/tor/JavaLibNetworkManager.java

...n/java/org/briarproject/mailbox/core/tor/JavaTorModule.kt

...java/org/briarproject/mailbox/core/tor/JavaTorPlugin.java

...ain/java/org/briarproject/mailbox/lib/JavaLibComponent.kt