Add `.editorconfig` validation @samtholiya (#896)

what

• Added functionality to atmos validate to validate against the .editorconfig file if it is defined
• Integrated the editorconfig-checker library to perform the validation
• Updated docs

why

• The change ensures that the .editorconfig file is validated, which helps maintain consistency in code formatting across teams.
• By incorporating editorconfig-checker, the validation process becomes more comprehensive, ensuring that both OPA/JSON schemas and editor configuration are correct
• This update was made to improve development workflow by catching formatting issues early during the validation process

Add Support for Testing Golden Snapshots @osterman (#939)

what

• Generate snapshots locally & commit them with the -regenerate-snapshots argument
• Test for changes by comparison golden snapshots with output
• Support TTY emulation (pty)
• Add support for !not tag to negate conditions
• Add a JSON schema for the test cases (to avoid silent failures)

why

• Too hard to add thorough tests for command line invocations