Conform more to command line standards

[ericwb]

Is your feature request related to a problem? Please describe. A nicely written standard around command lines is available.. Bandit should strive to conform to these standards where possible.

For more info, see: https://clig.dev/

TODOs:

• [x] Display help text when passed no options, the -h flag, or the --help flag. #814
• [x] Display a concise help text by default.
• [ ] Provide a support path for feedback and issues. A website or GitHub link in the top-level help text is common.
• [ ] In help text, link to the web version of the documentation.
• [ ] In help, Lead with examples.
• [ ] Display the most common flags and commands at the start of the help text.
• [ ] Use formatting in your help text.
• [ ] If the user did something wrong and you can guess what they meant, suggest it.
• [ ] Display output as formatted JSON if --json is passed.
• [x] Disable color if your program is not in a terminal or the user requested it. The NO_COLOR environment variable is set, the TERM environment variable has the value dumb, the user passes the option --no-color. #813
• [ ] Use a pager (e.g. less) if you are outputting a lot of text.
• [ ] Make it effortless to submit bug reports.
• [ ] Use standard names for flags, if there is a standard.