Add way for consumers to incorporate seed changes into repos created using the seed

[wise-king-sullyman]

I'm not sure yet what this could potentially look like, but it would be great if repos created using the extension seed had an easy way of "upgrading" their seed version to pull in new features or fixes.

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Jira Issue: PF-2100

[jessiehuff]

Possible solutions: code mods, node script

Lower priority, enhancement (can currently add it by hand)