Fix incorrect spacing when pretty-printing @_documentation

With attribute such as `@_documentation(visibility: private)`, swift-format incorrectly prints no spacing between `visibility` and `private`.

Author: dduan

Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift

@@ -1799,6 +1799,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
+  override func visit(_ node: DocumentationAttributeArgumentSyntax) -> SyntaxVisitorContinueKind {
+    after(node.colon, tokens: .break(.same, size: 1))
+    return .visitChildren
+  }
+
   override func visit(_ node: AvailabilityLabeledArgumentSyntax) -> SyntaxVisitorContinueKind {
     before(node.label, tokens: .open)
 

Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift

@@ -26,6 +26,23 @@ final class AttributeTests: PrettyPrintTestCase {
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 60)
   }
 
+  func testAttributeParamSpacingInDocVisibility() {
+    let input =
+      """
+      @_documentation(  visibility   :private )
+      func f() {}
+      """
+
+    let expected =
+      """
+      @_documentation(visibility: private)
+      func f() {}
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 60)
+  }
+
   func testAttributeBinPackedWrapping() {
     let input =
       """