Change layout of rust struct/imports/func params to vertical

[svix-mman]

Purely a formatting change.

I added these 3 lines to the rustfmt config in the rust sdk and in the cli.

fn_params_layout = "Vertical"
struct_lit_width = 0
imports_layout = "Vertical"
fn_call_width = 0

This makes all function calls, struct literal instantiation, imports, function prams to be formatted vertically. It's a little uglier, but I don't care so much about generated code 🤷

Part of my long term goal to not need rustfmt at all, will minimize the diff in an upcoming PR.

[svix-mman]

Not sure if I really want to do this, maybe I can generate nicely formatted code by hand 🤷