feature: Show builtin actions when no action is provided

[jarviliam]

Describe what this PR does / why we need it

Provides a QOL feature to show the list of builtin actions when no action is provided.

Does this pull request fix one issue?

Fixes #377

Describe how you did it

Added the config option enable_builtin which when enabled runs Octo actions when the user runs the default Octo command.

Describe how to verify it

When turned off the behavior of Octo should be the same. When enabled it should run Octo actions

Special notes for reviews

I've set the default behavior of it to be off but maybe it should just be on by default and just remove the error message when no action is provided? 🤔

[pwntester]

Thanks!