Add a convenience init to ClosureCaptureSyntax

**Summary**
This adds a convenience init to ClosureCaptureSyntax that adds equal
token if the provided `name` is not nil.

It's supposed to be used by developers, so it omits the unexpected
tokens.

Related: apple#1984

Sources/SwiftSyntax/Convenience.swift

@@ -10,6 +10,33 @@
 //
 //===----------------------------------------------------------------------===//
 
+extension ClosureCaptureSyntax {
+
+  /// Creates a `ClosureCaptureSyntax` with a `name`, and automatically adds an `equal` token to it since the name is non-optional.
+  ///
+  /// - SeeAlso: ``ClosureCaptureSyntax/init(leadingTrivia:_:specifier:_:name:_:equal:_:expression:_:trailingComma:_:trailingTrivia:)``.
+  ///
+  public init(
+    leadingTrivia: Trivia? = nil,
+    specifier: ClosureCaptureSpecifierSyntax? = nil,
+    name: TokenSyntax,
+    equal: TokenSyntax = TokenSyntax.equalToken(),
+    expression: some ExprSyntaxProtocol,
+    trailingComma: TokenSyntax? = nil,
+    trailingTrivia: Trivia? = nil
+  ) {
+    self.init(
+      leadingTrivia: leadingTrivia,
+      specifier: specifier,
+      name: name as TokenSyntax?,
+      equal: equal,
+      expression: expression,
+      trailingComma: trailingComma,
+      trailingTrivia: trailingTrivia
+    )
+  }
+}
+
 extension EnumCaseParameterSyntax {
 
   /// Creates an `EnumCaseParameterSyntax` with a `firstName`, and automatically adds a `colon` to it.

Tests/SwiftSyntaxTest/SyntaxTests.swift

@@ -133,4 +133,12 @@ public class SyntaxTests: XCTestCase {
     let node = EnumCaseParameterSyntax(firstName: "label", type: TypeSyntax("MyType"))
     XCTAssertEqual(node.formatted().description, "label: MyType")
   }
+
+  public func testClosureCaptureSyntaxConvenienceInitWithEqual() {
+    let noNameClosureCapture = ClosureCaptureSyntax(expression: ExprSyntax("123"))
+    XCTAssertEqual(noNameClosureCapture.formatted().description, "123")
+
+    let node = ClosureCaptureSyntax(name: "test", expression: ExprSyntax("123"))
+    XCTAssertEqual(node.formatted().description, "test = 123")
+  }
 }