servo: Merge #17749 - Extra space check (from SergeevPavel:extra-space-check); r=jdm

<!-- Please describe your changes on the following line: -->
Add tidy check for keywords with more than one space afterwards.

---
<!-- 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 #17700 (github issue number if applicable).

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

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Source-Repo: https://github.com/servo/servo
Source-Revision: 7d95fb8e49dd0eb9fa9efb9d70008f5f9bf20a83

servo/python/tidy/servo_tidy_tests/rust_tidy.rs

@@ -72,4 +72,10 @@ impl test {
       } else { // Should not trigger
           "false"
       } // Should not trigger
+
+    if  true { // Double space after keyword
+        42
+    } else {
+        let xif = 42 in {  xif  } // Should not trigger
+    }
 }

servo/python/tidy/servo_tidy_tests/test_tidy.py

@@ -95,6 +95,7 @@ class CheckTidiness(unittest.TestCase):
 
     def test_rust(self):
         errors = tidy.collect_errors_for_files(iterFile('rust_tidy.rs'), [], [tidy.check_rust], print_text=False)
+        self.assertEqual('extra space after use', errors.next()[2])
         self.assertEqual('extra space after {', errors.next()[2])
         self.assertEqual('extra space before }', errors.next()[2])
         self.assertEqual('use statement spans multiple lines', errors.next()[2])
@@ -133,6 +134,7 @@ class CheckTidiness(unittest.TestCase):
         self.assertEqual('no = in the beginning of line', errors.next()[2])
         self.assertEqual('space before { is not a multiple of 4', errors.next()[2])
         self.assertEqual('space before } is not a multiple of 4', errors.next()[2])
+        self.assertEqual('extra space after if', errors.next()[2])
         self.assertNoMoreErrors(errors)
 
         feature_errors = tidy.collect_errors_for_files(iterFile('lib.rs'), [], [tidy.check_rust], print_text=False)