Fix clippy::println_empty_string, clippy::while_let_on_iterator, clippy::while_let_on_iterator lint style violations (#36613)

Related: #36577

Release Notes:

- N/A

crates/vim/src/command.rs

@@ -1492,7 +1492,7 @@ impl OnMatchingLines {
         let mut search = String::new();
         let mut escaped = false;
 
-        while let Some(c) = chars.next() {
+        for c in chars.by_ref() {
             if escaped {
                 escaped = false;
                 // unescape escaped parens

crates/vim/src/normal/increment.rs

@@ -274,9 +274,9 @@ fn find_boolean(snapshot: &MultiBufferSnapshot, start: Point) -> Option<(Range<P
     let mut end = None;
     let mut word = String::new();
 
-    let mut chars = snapshot.chars_at(offset);
+    let chars = snapshot.chars_at(offset);
 
-    while let Some(ch) = chars.next() {
+    for ch in chars {
         if ch.is_ascii_alphabetic() {
             if begin.is_none() {
                 begin = Some(offset);