[21.05] Fix copying text in workflow editor

[mvdbeek]

The only text we could copy had to be within input boxes, but we may
want to also copy text from the error / upgrade message modal or from
the help text or other links.
So if there's currently any highlighted text we skip the workflow copy
logic.
Copying nodes continues to work correctly, one only needs to make sure we're not currently highlighting text or that we're within a input element.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  Open a workflow and highlight any tool help text or tool label, and paste it into another window.

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