feat: add process module with arguments and allArguments static methods

- Introduce new 'process' module exposing a Process class with foreign static methods for accessing command-line arguments.
- Implement processSetArguments in main.c to store argc/argv, and processAllArguments in process.c to return them as a Wren list.
- Add --help flag support to CLI, printing usage with optional arguments.
- Include documentation for Process.arguments and Process.allArguments, plus module index and template updates.
- Register process module in modules.c and add Xcode project references for new source files.
- Add test scripts for allArguments and arguments, verifying list type, count, and expected values.

test/process/all_arguments.wren

@@ -0,0 +1,11 @@
+import "process" for Process
+
+var args = Process.allArguments
+System.print(args is List) // expect: true
+System.print(args.count)   // expect: 2
+
+// Includes wren executable and file being run.
+System.print(args[0].endsWith("wrend")) // expect: true
+System.print(args[1]) // expect: test/process/all_arguments.wren
+
+// TODO: Test passing additional args once we have an API to spawn a process.

test/process/arguments.wren

@@ -0,0 +1,6 @@
+import "process" for Process
+
+// No additional arguments are passed to the test.
+System.print(Process.arguments) // expect: []
+
+// TODO: Test passing additional args once we have an API to spawn a process.