Autofix on mutating constant

[DivergentClouds]

Due to #1607 if you write something like var foo: usize = 0 and then you run autofix (my autofix runs on save) it will turn into const foo: usize = 0 and if you mutate it later by adding foo += 1 for example, you will get an error for attempting to assign to a constant.

[leecannon]

I don't think auto const -> var fits zig.

[nektro]

this is zls not zig

but if that's still your opinion, then the var->const autofix shouldn't be in zls either

[DivergentClouds]

I think the zls autofix should change how the var to const works then to add a _ = &foo instead of making it const. I don't want to have to fight with the language server when I just want to save in middle of writing my code.

[Techatrix]

fixed by #1652