Treat ; as a terminator rather part of a glued expression

[gbbosak]

The following code fails in rust-analyzer, but passes in rustc, using the "log" crate with the "kv" feature enabled:

fn main() {
let written:i32 = 5;
log::warn!(written:%; "Test");
}

This fails, because :%; is treated as a single glued token, rather than the :% glued expression followed by a ; terminator.

Fix this by not gluing ; to match rustc behavior.

[Veykril]

This looks like it should't change anything for the semicolon token, so that points to a more general bug in my eyes with our glueing infra structure

[gbbosak]

This is needed because we incorrectly treat ; as a possible glued token, when it shouldn't be as it's an expression terminator. It does fix the bug in the repro mentioned above.

[gbbosak]

To clarify, why this works is that we do a 3-token at a time lookahead, and we see :%; which without this matches the rule for % followed by : followed by % (which is allowed because it's not forbidden by the match expression).

[Veykril]

I see, it is clear that this entire part is messy and needs to be redone at some point (likely by #17830) but given this improves things right now lets merge it, thanks!