Fix some bugs found via fuzzing

* Keywords need to still be recognized if they're followed by ',' as well as a bunch of other operator characters. Notably missing from this list is '-', since that would mess up expect-fx currently.
* Smattering of niche cases of formatting bugs (either non-idempotency, leading to different code, or leading to unparsable code)
* One missing indent call in fmt_collection leading to a panic

crates/compiler/parse/src/parser.rs

@@ -1056,7 +1056,11 @@ where
         // the next character should not be an identifier character
         // to prevent treating `whence` or `iffy` as keywords
         match state.bytes().get(width) {
-            Some(next) if *next == b' ' || *next == b'#' || *next == b'\n' || *next == b'\r' => {
+            Some(
+                b' ' | b'#' | b'\n' | b'\r' | b'\t' | b',' | b'(' | b')' | b'[' | b']' | b'{'
+                | b'}' | b'"' | b'\'' | b'/' | b'\\' | b'+' | b'*' | b'%' | b'^' | b'&' | b'|'
+                | b'<' | b'>' | b'=' | b'!' | b'~' | b'`' | b';' | b':' | b'?' | b'.',
+            ) => {
                 state = state.advance(width);
                 Ok((MadeProgress, (), state))
             }