to_clipboard() should ignore display options

When the frame is too wide or too long, summary/expand_repr kick in
and the contents of the clipboard are unusable.

Could perhaps introduce an option to enforce a limit on row count (10,000? 100,000? )
and/or add a `force` keyword in `to_clipboard()` since copying a huge amount into the 
clipboard can hang.

now that it uses to_csv by default (#5070 ), it's only relevent with `excel=false`
