Disabled property for the nav buttons doesn't support RTL

[RotemCarmon]

Describe the bug
The disabled property for the nav buttons doesn't support RTL. When isRTL is true and infinite is false, the nav disabled value is still calulated based on LTR values.

When the first image is presented, the left nav is disabled, and the right nav is navigating to the last image in the gallery. When the last image is presended, the rigth nav is disabled, and the left nav is navigating to the first image in the gallery. So I can only navigate between the first and the last image in the gallery.

Image Gallery Version
v 1.3.0

To Reproduce
Steps to reproduce the behavior:

1. create an image gallery using react image gallery package.
2. set the attributes isRTL={true} infinite={false}
3. navigate between the images using the nav buttons

Expected behavior
When on the first image of the galllery the left nav should be disabled. When on the last image of the gallery the right nav should be disabled.

Client info (please complete the following information):\

• OS: Macbook pro 2021
• Browser: Chrome