Add version command to CLI

[melonattacker]

This pull request adds a version command and related flags to the Threat Thinker CLI, allowing users to easily check the installed version of the tool. The implementation includes robust logic to determine the version from package metadata or fallback to the pyproject.toml file, and comprehensive tests to ensure correct behavior. Documentation is also updated to reflect the new feature.

CLI Version Command and Flags:

• Added a version subcommand and -v/--version/--verison flags to the CLI, displaying the installed Threat Thinker version. The version is determined from package metadata or falls back to pyproject.toml if necessary. [1] [2] [3]

Documentation Updates:

• Updated README.md and docs/cli.md to document the new version command and usage examples. [1] [2]

Testing Enhancements:

• Added tests to verify the output of the version command and flags, as well as the version detection logic. [1] [2]