[Tweak] Copy function change behavior

At the moment we have the copy button function in Crayon. It’s outdated. For example on mobile devices and tablets, it will not work as expected.

What it does now:
When clicking on copy button, it goes to plain text mode. All text get selected. You get a message to copy text with control C and paste with V.

How it should be:
When clicking on copy button, it will show show that the text is copied. The text will be copied to the clipboard.

What do you think?