feat: assert size of message and batch

Description

Added the feature to ensure individual message size is not greater than 32KB.
Added the feature to ensure batch size is not greater than 500KB.
Added new API deleteMessagesSync to delete the message from the local DB/storage in a sync way.

Fixes # (issue)

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update
Checklist:
[ ] Version upgraded (project, README, gradle, podspec etc)
[ ] My code follows the style guidelines of this project
[ ] I have performed a self-review of my own code
[ ] I have commented my code, particularly in hard-to-understand areas
[ ] I have added unit tests for the code
[ ] I have made corresponding changes to the documentation