Fix remaining test failures for Gradle 8 and 9 compatibility

- Fix RequireJsTask: Add ProcessBuilder fallback for test contexts where project.javaexec is not available
  - Ensure all ProcessBuilder command elements are explicitly converted to strings
  - Consume output streams to prevent process from hanging

- Fix JsPluginFunctionalTest: Implement getPatternSetFactory() in TestTask class
  - Required for SourceTask subclasses in Gradle 9
  - Inject PatternSetFactory via constructor

- Fix JsHintTask: Refactor warning detection logic to match JSHint behavior
  - Add setCheckSymbols(true) and setCheckGlobalThis(false) to compiler options
    to enable proper undefined variable detection
  - Implement custom BasicErrorManager to capture all Closure Compiler diagnostics
  - Refine warning detection logic to differentiate between lint warnings and
    critical warnings (undefined variables, unused variables, strict mode violations)
  - When JSHint options (undef, unused, strict) are enabled, fail on relevant warnings
  - When no options are enabled, only fail on critical warnings (undefined variables)
  - Filter out lint-only warnings (using var, missing semicolon) when checking for
    critical issues
  - Add comprehensive debug logging for diagnostic group configuration and
    warning detection

- Fix JavaScriptExtension: Use source.configure(closure) for proper delegation

All tests now pass with both Gradle 8.14.3 and Gradle 9.2.1.

Author: gamma

src/main/groovy/com/eriwen/gradle/js/JavaScriptExtension.groovy

@@ -22,8 +22,8 @@ class JavaScriptExtension {
     }
 
     void source(Closure closure) {
-        closure.delegate = source
-        closure.resolveStrategy = Closure.DELEGATE_FIRST
-        closure.call(source)
+        // Configure the container - use the container's configure method directly
+        // This allows dynamic method calls like custom { } to work
+        source.configure(closure)
     }
 }