`sway-fmt-v2` formatting should use `tokens` directly from `sway-parse`

[eureka-cpu]

Instead of something like:

formatted_code.push_str("}\n");

we should do:

use sway_parse::token::Delimiter;

formatted_code.push_str(&format!("{}\n", Delimiter::Brace.as_close_char());

As seen in #2061