feat: Change default isolation mode from 'restrictive' to 'cfg'

[cidrblock]

Closes: #338

Summary

This PR changes the default isolation mode from 'restrictive' to 'cfg' to provide better workspace isolation by default.

Changes Made

• Updated default isolation mode: Changed from 'restrictive' to 'cfg' in arg_parser.py
• Updated test cases: Modified tests to explicitly specify --im restrictive where the restrictive mode behavior is specifically being tested
• Maintained backward compatibility: All existing functionality remains available through explicit flags

Why This Change?

The 'cfg' isolation mode provides better workspace isolation by creating/updating an ansible.cfg file in the current working directory. This approach is more user-friendly and provides clearer workspace boundaries compared to the 'restrictive' mode.

Testing

• All existing tests have been updated to maintain their intended behavior
• Tests that specifically need restrictive mode now explicitly specify it
• No breaking changes to the API - users can still use any isolation mode via the --im flag

Impact

• Users upgrading: Will get 'cfg' isolation mode by default instead of 'restrictive'
• Existing scripts: Can continue to work by explicitly specifying --im restrictive if needed
• New users: Will get a better default experience with clearer workspace isolation