Support encryption hook

[marandaneto]

Problem Statement

If events contain sensitive data, and the data is stored in the device, the device is sandboxed. Still, if you want everything to be encrypted, you can encrypt events before flushing them to the disk and decrypting them before sending them to the network.

Solution Brainstorm

https://posthog.com/docs/libraries/android#all-configuration-options

// Hook for encrypt and decrypt events
// Devices are sandbox already
// Defaults to no encryption
encryption = object : PostHogEncryption { ... }