[Feature] Add a gem swap step

[Aria Edmonds]

For example, in the usual caster levelling setup - Rolling magma until lvl 28 where you swap to arma brand,

It would be great for there to be a way to have a respec step where it tells you to go back through to act 2 and buy the act 2 gems, etc etc. This would alleviate the currency pressure early where you might be buying gems with the few transmutes you have for something you won't be swapping to for another 15 levels.

There's also a minor optimization where you can take the gems you need from the swap as quest rewards, if your initial levelling setup doesn't take anything from there.