Auto merge of #18553 - mdboom:tidy-support-multiline-strings, r=wafflespeanut

Make tidy aware of Rust multiline strings

<!-- Please describe your changes on the following line: -->
This makes the internal tidy script properly ignore the contents of Rust multiline strings.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #18551 (github issue number if applicable).

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/layout/generated_content.rs

@@ -137,7 +137,7 @@ impl<'a> InorderFlowTraversal for ResolveGeneratedContent<'a> {
 }
 
 /// The object that mutates the generated content fragments.
-struct ResolveGeneratedContentFragmentMutator<'a,'b:'a> {
+struct ResolveGeneratedContentFragmentMutator<'a, 'b: 'a> {
     /// The traversal.
     traversal: &'a mut ResolveGeneratedContent<'b>,
     /// The level we're at in the flow tree.
@@ -148,7 +148,7 @@ struct ResolveGeneratedContentFragmentMutator<'a,'b:'a> {
     incremented: bool,
 }
 
-impl<'a,'b> ResolveGeneratedContentFragmentMutator<'a,'b> {
+impl<'a, 'b> ResolveGeneratedContentFragmentMutator<'a, 'b> {
     fn mutate_fragment(&mut self, fragment: &mut Fragment) {
         // We only reset and/or increment counters once per flow. This avoids double-incrementing
         // counters on list items (once for the main fragment and once for the marker).

components/layout/persistent_list.rs

@@ -69,7 +69,7 @@ impl<T> Clone for PersistentList<T> where T: Send + Sync {
     }
 }
 
-pub struct PersistentListIterator<'a,T> where T: 'a + Send + Sync {
+pub struct PersistentListIterator<'a, T> where T: 'a + Send + Sync {
     entry: Option<&'a PersistentListEntry<T>>,
 }
 

components/script_plugins/unrooted_must_root.rs

@@ -163,7 +163,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnrootedPass {
     }
 }
 
-struct FnDefVisitor<'a, 'b: 'a, 'tcx: 'a+'b> {
+struct FnDefVisitor<'a, 'b: 'a, 'tcx: 'a + 'b> {
     cx: &'a LateContext<'b, 'tcx>,
     in_new_function: bool,
 }