[OzzModz] Mark All Conversations 2.0.0 Patch Level 1

2.0.0 Patch Level 1:
- Fix: calculate optimal batch to avoid execution timeout errors

Changelog:

• Feature: added action to leave all conversations
• Fix: hide "mark all" button if no conversations available
• Fix: reset inlinemod cookie
• Fix: PHP < 7.2 compatibility

Added option to disable certain actions
Small refactor