ExitTest.find(withArguments:) -> ExitTest.findInEnvironmentForSwiftPM() (#346)

Rename the `ExitTest.find(withArguments:)` function because it doesn't
actually use command-line arguments in the current implementation.

### Checklist:

- [x] Code and documentation should follow the style of the [Style
Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md).
- [x] If public symbols are renamed or modified, DocC references should
be updated.

Author: grynspan

Sources/Testing/ExitTests/ExitTest.swift

@@ -213,19 +213,16 @@ extension ExitTest {
   /// recording any issues that occur.
   public typealias Handler = @Sendable (_ exitTest: borrowing ExitTest) async throws -> ExitCondition
 
-  /// Find the exit test function specified by the given command-line arguments,
-  /// if any.
-  ///
-  /// - Parameters:
-  ///   - args: The command-line arguments to this process.
+  /// Find the exit test function specified in the environment of the current
+  /// process, if any.
   ///
   /// - Returns: The exit test this process should run, or `nil` if it is not
   ///   expected to run any.
   ///
   /// This function should only be used when the process was started via the
   /// `__swiftPMEntryPoint()` function. The effect of using it under other
   /// configurations is undefined.
-  public static func find(withArguments args: [String]) -> Self? {
+  static func findInEnvironmentForSwiftPM() -> Self? {
     let sourceLocationString = Environment.variable(named: "SWT_EXPERIMENTAL_EXIT_TEST_SOURCE_LOCATION")
     if let sourceLocationData = sourceLocationString?.data(using: .utf8),
        let sourceLocation = try? JSONDecoder().decode(SourceLocation.self, from: sourceLocationData) {

Sources/Testing/Running/EntryPoint.swift

@@ -55,7 +55,7 @@ private import Foundation
       options.isVerbose = args.contains("--verbose")
 
 #if !SWT_NO_EXIT_TESTS
-      if let exitTest = ExitTest.find(withArguments: args) {
+      if let exitTest = ExitTest.findInEnvironmentForSwiftPM() {
         await exitTest()
         return exitCode.rawValue
       }

Sources/Testing/Running/XCTestScaffold.swift

@@ -161,7 +161,7 @@ public enum XCTestScaffold: Sendable {
 
 #if !SWT_NO_EXIT_TESTS
     // Exit test handling.
-    if let exitTest = ExitTest.find(withArguments: CommandLine.arguments()) {
+    if let exitTest = ExitTest.findInEnvironmentForSwiftPM() {
       await exitTest()
       exit(EXIT_SUCCESS)
     }