Add context menu to Web Chat send message box

[xieofxie]

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Is your feature request related to a problem? Please describe. I'm always frustrated when I can't right-click and paste in 'Type your message'

Describe the solution you'd like add context menu in 'Type your message' to support paste etc.

Describe alternatives you've considered

Additional context This is very useful when using Login prompt to copy-paste the validation code

[enhancement]