Add test cases verifying that invalid trailing comma syntaxes in list literals
(e.g. `[,]`, `[1,,]`, `[1,,2]`) and map literals (e.g. `{,}`, `{1:1,,}`, `{1:1,,2:2}`)
correctly produce compile errors when evaluated via Meta.eval in a Fiber.
Add a check in the map parsing function to break when encountering a closing brace after a comma, enabling trailing commas in map literals. Include a test case verifying that maps with trailing commas parse and execute correctly.
The benchmark directory is relocated from the project root into the test directory, and all scripts, documentation links, and gitignore paths are updated accordingly. The test runner is also refactored to explicitly walk subdirectories (core, io, language, limit) instead of using a single test root, and a new test/README.md is added to document the test suite structure. Additionally, the constructor test for the Foo class is updated to add a zero-arity constructor and adjust expected output strings.
