feat(Right-to-Left (RTL) Layout Support for Inbox

[SoheilHasankhani]

Description:

Issue Overview:
I propose the addition of a new feature to enhance Courier Inbox by introducing support for Right-to-Left (RTL) layouts. This improvement involves adding a "rtl" property of type boolean to the theme object in the inbox configuration.

Details:

Feature Description:

Introduce a "rtl" property to the theme object in the inbox configuration.
When set to true, the Courier Inbox layout will switch to Right-to-Left (RTL) mode.
This feature aims to enhance user experience for audiences that prefer RTL languages or layouts.