Handle Duplicate clauseId from Copy/Paste

[irmerk]

Linked Isues:

- MDE 88

- TSv2 82

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Is your feature request related to a problem? Please describe.
Incorporate any clause specific logic here from markdown-editor Issue 88

Currently, a uuidv4 is assigned to each clause template added into the markdown of the contract. Copying and pasting should recognize that as already existing and create a new uuidv4

Describe the solution you'd like
Possibly register multiple onPaste handlers on the underlying Slate editor. These are likely chained by the call to next(). Test what happens on paste of HTML which contains an existing clause <div>.

When a clause template is pasted, TSv2 should check to see if a clause template exists in the pasted text. If so, check if that clause template is already in the contract. If so, assign a new uuidv4 to this clause template.

Describe alternatives you've considered
A good starting point should be SlateJS's onPaste plugin
Already in the code here

Additional context
N/A

[irmerk]

Further issues should consider:

• Handling different transfer.type situations

  • Editor instance (Slate) to another editor instance (Slate)
  • Raw HTML (Chrome to VSCode to Chrome)
  • Editor instance (Slate) to Google Docs and back (recognize <clause> formatting)

• Ensure onPaste handlers are not doubling up work for any transfer.type cases

  • @accordproject/cicero-ui/src/plugins/ClausePlugin
  • @accordproject/markdown-editor/src/SlateAsInputEditor

• What fragment.type results when copying pasting from one editor to another instance of an editor?

  • fragment as a transfer.type is a Slate DOM block fragment, not HTML anymore, so copying and pasting from the same editor into itself should be a fragment
  • However, copying pasting from one editor to another instance of an editor may result in HTML or fragment, needs experimentation

• Preserve formatting, if H1 in HTML, we should be preserving the formatting

  • Slate has a mechanism for mapping from HTML tags to Slate blocks here