LiveObject: update proguard.txt for the module

[sacOO7]

• Similar to android-proguard, we either need to update existing proguard.txt or include one in the liveobjects module ( since we are using reflection for serialization and deserialization )
• Reference PR -> [ECO-5386] Liveobjects serialization using msgpack-jackson #1101

┆Issue is synchronized with this Jira Task by Unito

[sacOO7]

This will need running demo app with proguard enabled to identify relevant issues.

[sacOO7]

Surely, need to add a proguard skip for classes mentioned in LiveObjectsHelper.java, since it dynamically initializes the classes at runtime.

[sacOO7]

Addressed as a part of #1154