Add persistenceDirectory config option for controlling event/session storage

[fractalwrench]

Goal

Adds a persistenceDirectory config option that controls where events/sessions are stored. By default this remains context.cacheDir. This gets us one step closer to supporting Clients in multiple processes.

Changeset

• Added persistenceDirectory option to Configuration that allows users to set a custom File
• Updated FileStore constructor to take a File that specifies the directory where reports should be persisted. If it is not possible to write to the directory an error is logged
• Refactored existing storage code to use greater use of File rather than String for calculating paths
• Updated NativeInterface.getReportPath() to use config.persistenceDirectory when calculating storage directory

Testing

• Added unit tests to assert that persistenceDirectory can have its values set on the public API as expected
• Assert that persistenceDirectory is set to the context.cacheDir by default
• Refactor Event/SessionStoreMaxLimitTest to be unit tests, as FileStore no longer requires a Context and can therefore run on the JVM (this is much faster)
• Updated tests to use a custom persistenceDirectory and Files rather than Strings where necessary

[bugsnagbot]

Android notifier sizes

Format	Size impact of Bugsnag (kB)	Size impact of Bugsnag when Minified (kB)
APK	1442.05	1361.31
arm64_v8a	369.25	287.32
armeabi	348.77	266.85
armeabi_v7a	332.39	250.47
x86	410.2	328.27
x86_64	389.73	307.81

Generated by 🚫 Danger