chore(frontents/lean/parser.cpp): change binder collection order (#656)
chore(frontents/lean/parser.cpp): change binder collection order (#656)

This changes the binder order of multiple variable binder collections like `∀ (x y < n), true` from `∀ (x y : _) (_ : x < n) (_ : y < n), true` to `∀ (x : _) (_ : x < n) (y : _) (_ : y < n), true`. This makes it easier to expand these binders into simple binder collections as in `∀ (x y < n), true ~> ∀ x < n, ∀ y < n, true`; otherwise the multiple-variable binder collection syntax needs special attention in mathlib4 and mathport.

Incidentally, there are apparently zero uses of this syntax in the core library and test suite, but mathlib probably has a couple occurrences that will have to be adjusted following this change.



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