Better Mighty Chain

[ArthurKun21]

Preparation

• No one has asked for this feature before in other issues (even the closed ones)

Describe the feature

I copied the initial implementation before, but think it is about time to copy the new changes.

Ain't gonna lie, it is a bit too complex and I only want to do a minimum effort.

Custom Selection from #192 is much easier and more likely to be used anyways.

https://redirect.github.com/Fate-Grand-Automata/FGA/pull/2087