trim whitespace in doxygen formatter assertion (#1329)

rdar://163704908

Author: QuietMisdreavus

Tests/SwiftDocCTests/Semantics/DoxygenTests.swift

@@ -96,7 +96,7 @@ class DoxygenTests: XCTestCase {
         let symbol = try XCTUnwrap(node.semantic as? Symbol)
 
         XCTAssertEqual(symbol.abstract?.format(), "This is an abstract.")
-        XCTAssertEqual(symbol.discussion?.content.map { $0.format() }, [
+        XCTAssertEqual(symbol.discussion?.content.map { $0.format().trimmingCharacters(in: .whitespacesAndNewlines) }, [
             #"\abstract This is description with abstract."#,
             #"\discussion This is a discussion linking to ``doc://unit-test/documentation/ModuleName/AnotherClass`` and ``doc://unit-test/documentation/ModuleName/AnotherClass/prop``."#,
             #"\note This is a note linking to ``doc://unit-test/documentation/ModuleName/Class3`` and ``Class3/prop2``."#