Use DI for AccountSettings and Android tests

[rfc2822]

• Use Hilt for AccountSettings.
• Use Hilt for Android tests when things need to be injected.

Findings:

• There's no guaranteed order for multiple @Before methods in JUnit tests, so we should only have one @Before fun setup() per test class. This setup method runs AndroidHiltRule.inject() first and can then initialize other things. Test variables that depend on the Context need to be declared by lazy because the Context will only be available after the Hilt rule is run.
• In Android tests using Hilt (@HiltAndroidTest), we should always inject the application context instead of getting it from the instrumentation. Otherwise Hilt may have stored another (wrapped or whatever) Application as application context and then things like EntryPointAccessors.fromApplication won't work properly.
• We should always inject @ApplicationContext val context: Context instead of an Application for the same reason.