Push (EPNS)v0.13

What changed

• RetentionAdded push notifications for chat features
• RetentionUpgraded push notifications for channels
• UXAdded support for filtering channel categories
• New featureEnabled file downloads within chat
• PerformanceGeneral bug fixes and code refactoring

Original release notes

- Chat feature push notifications.
- Channels push notifications upgrades.
- Channel categories filter support.
- File download in chat.
- Bug fixes and refactoring.