perf(parser): make pushing tokens faster (#19960)

Use `Vec::push_fast` method (introduced in #19959) for pushing to the tokens `Vec`. We allocate sufficient capacity upfront in the `Vec`, so it should never need to grow.

`Vec::push_fast` makes the "need to grow" path cold and `#[inline(never)]`, which should reduce the size of `Lexer::finish_next`, and help the branch predictor make accurate predictions.

+1% on benchmark for parsing with tokens in CodSpeed. *Possible* it'll have more impact in real world as CodSpeed doesn't take branch predictor into account in its simulations.

crates/oxc_parser/src/lexer/mod.rs

@@ -302,7 +302,11 @@ impl<'a, C: Config> Lexer<'a, C> {
         let token = self.token;
         if self.config.tokens() {
             match mode {
-                FinishTokenMode::Push => self.tokens.push(token),
+                FinishTokenMode::Push => {
+                    // We allocated sufficient capacity in the `Vec` for all tokens at the start.
+                    // `push_fast` is optimized for the "doesn't need to grow" case.
+                    self.tokens.push_fast(token);
+                }
                 FinishTokenMode::Replace => {
                     debug_assert!(
                         self.tokens.last().is_some_and(|last| last.start() == token.start())