Site Icon: Preview when cropping an image is broken in RTL

[ocean90]

• When cropping an image in the media modal the app icon preview doesn't get always updated. The image wrapper needs a direction: ltr wrapper.
• Same for the favicon, but this is more fun. It updates the wrong preview. Instead of updating the one in the media modal it updates the one in the customizer panel because both are using the same ID.

[ocean90]

In 37964:

Customize: Fix site icon preview in RTL.

• Set the direction of previews to LTR.
• Remove the ID attribute from the favicon preview in the customizer panel. The preview in the media modal uses the same ID which prevented updating the correct favicon preview.

Fixes #37286.