[Feature Request] Add option to pin screenshot over apps

[heiwiper]

Use case :

• Avoid opening two apps side by side for when you only need to see something from one of the opened apps and interact with the other one.
• Avoid scrolling back to check something when you're reading from a PDF file for example and there's a formula or graph somewhere which you are supposed to read its interpretation while still looking at it.

Options :

• The pinned screenshot should be resizable when you drag its borders.
• The screenshot should be movable when you drag it.
• The feature should be optional for users who are not willing to grant overlay permission.