Add support for Dynamic Data Exchange (DDE) references

[axemonk]

e.g., the following reference and its three components should be scoped ("component" pseudo scopes for ease of reference):

=hel|lo!'R1C1:R2C2'
'^^^ component 1
'    ^^ component 2
'       ^^^^^^^^^^^ component 3

I have no idea what the naming rules for comp. 1 and 2 are or whether they can be escaped with ' like sheet names.
Also don't know whether component 3 can be A1 reference style.
And not to mention, I have no idea what the hell this feature actually does. More research required.

[michaelblyons]

Every time I try to write a highlighter for some format I use, I discover language features I had never heard of. Every single time.

[axemonk]

el oh el (pic related).

I do eventually want to give adding support for this a decent try, but if ChatGPT is to be trusted, this is ultra low priority.