Sandbox Mode to instruct baapan not to 'require' modules outside workspace directory

[deepal]

The standard baapan REPL require resolves a required module path starting from the current directory's node_modules directory all the way up to the parent directories (and some additional directories) until the module is located. This behaviour is identical to the original Node REPL.

If baapan Sandbox mode is enabled, require will not try to resolve a 3rd party module's path outside the working directory. If the module is not installed in the workspace, it should try to install it to the workspace. However, this behaviour should not affect local modules (relative/absolute paths) or native modules