Wrap multi-line function declarations before the last paren

[mike-at-home]

Summary

This PR updates our Swift formatting rules for multiline function declarations to place the closing parenthesis and return type on the same line, immediately followed by the opening brace. This format aligns with Swift community conventions, improves readability, and results in cleaner diffs during edits and refactors.

(Note: this PR does not address call-site wrapping, which will be addressed in another proposal)

---

Reasoning

The current style:

public func executeRequest(
  _ request: URLRequest,
  onSuccess: @escaping (ModelType, Bool) -> Void,
  onFailure: @escaping (Error) -> Void)
  -> URLSessionCancellable
{
  ...
}

is replaced with:

public func executeRequest(
  _ request: URLRequest,
  onSuccess: @escaping (ModelType, Bool) -> Void,
  onFailure: @escaping (Error) -> Void
) -> URLSessionCancellable {
  ...
}

Benefits

• Easier, clearer single-line to multiline conversion
  Converting this:

public func executeRequest(_ request: URLRequest, onSuccess: @escaping (ModelType, Bool) -> Void, onFailure: @escaping (Error) -> Void) -> URLSessionCancellable {
  ...
}

With the old format:

-public func executeRequest(_ request: URLRequest, onSuccess: @escaping (ModelType, Bool) -> Void, onFailure: @escaping (Error) -> Void) -> URLSessionCancellable {
+public func executeRequest(
+  _ request: URLRequest,
+  onSuccess: @escaping (ModelType, Bool) -> Void,
+  onFailure: @escaping (Error) -> Void)
+  -> URLSessionCancellable
+{

With the new format:

-public func executeRequest(_ request: URLRequest, onSuccess: @escaping (ModelType, Bool) -> Void, onFailure: @escaping (Error) -> Void) -> URLSessionCancellable {
+public func executeRequest(
+  _ request: URLRequest,
+  onSuccess: @escaping (ModelType, Bool) -> Void,
+  onFailure: @escaping (Error) -> Void
+) -> URLSessionCancellable {

• Simplifies adding or removing parameters
  Using trailing commas avoids touching unrelated lines:

public func createUser(
  name: String,
  email: String,
) -> User

Adding a parameter:

 public func createUser(
   name: String,
   email: String,
+  age: Int,
 ) -> User

Removing a parameter:

 public func createUser(
   name: String,
-  email: String,
 ) -> User

• Matches single-line function style
  This keeps multiline functions visually consistent with non-wrapped ones:

public func reset() -> Bool {
  ...
}

• Community alignment
  This style is the default in tools like swift-format and increasingly the standard in open source Swift projects.

---

Conclusion

This change brings us in line with community norms and improves the day-to-day development experience — especially when editing, reviewing, and refactoring function declarations.