Add "branch" scope type

[pokey]

• Partially addresses Add "branch" scope type #1173
• Split from Pattern matching support #831

Checklist

	Python	Rust	Java	Typescript	C++	C#
Switch-case	✅	✅	✅	✅
If-else	✅	✅		✅
Try-catch	✅	N/A		✅
Ternary	✅	✅		✅

• I have added tests
• I have updated the docs and cheatsheet
• I have not broken the cheatsheet

Co-authored-by: Michael Doronin warrior2031@mail.ru

[pokey]

Closing until someone has bandwidth to finish this PR

[pokey]

After discussion in meet-up:

Just kidding; let's get this thing in for the languages that exist here. more useful to at least have it functional in some places

[auscompgeek]

We should also test:

• Python for/else and while/else
• Rust if let and let/else

[auscompgeek]

It feels a bit weird for branch to work on the try block itself 🤷

[pokey]

Yeah I'm not entirely sure what the use case for that is tbh 😅, but seemed consistent, and maybe someone would want to use it with the copy action?

[pokey]

• Rust if let and let/else

Unfortunately that is blocked on #1201 😕

[auscompgeek]

Unfortunately that is blocked on #1201 😕

Ah, I was afraid as such.

[auscompgeek]

I think the implicit "this" change got cherry-picked into this branch for some reason, but otherwise LGTM.

I presume it should be trivial to reuse the if/else matchers for Java and C++ like we did for Rust, and I hope the same for try/catch, so might be worth doing it here anyway.

[auscompgeek]

nit: any reason this is listed in this order in particular?

[pokey]

Not really. I should prob file a follow-up to alphabetise; didn't want to mess with the diff

[pokey]

I think the implicit "this" change got cherry-picked into this branch for some reason, but otherwise LGTM.

Strange. That's already merged into main anyway, but looks like the parentage is strange here; I'll have a look

I presume it should be trivial to reuse the if/else matchers for Java and C++ like we did for Rust, and I hope the same for try/catch, so might be worth doing it here anyway.

Unfortunately not 😕. Java, C#, and C++ don't have a special node for else clauses, so the logic gets more complicated. Should be doable, but not just a quick afterthought like one would hope. I'd be inclined to leave for follow-up work