Redact Screenshots via View Hierarchy

[kahest]

see getsentry/team-mobile#178

[romtsn]

For this to work we'll have to move redaction code from sentry-android-replay to sentry-android-core, but currently that code is in Kotlin so we either have to convert it back to Java or convert -core to Kotlin (finally)

[kahest]

As discussed, SR is top priority, so we'll only tackle this once/if we know it doesn't put SR timeline at risk at all

[romtsn]

We can probably start with just moving this code in Kotlin but without stdlib, that should be easy