Add include-mode to select which operations to include

[svix-mman]

Keep the same default behavior to only include public operations

Will be useful when we generate the internal JS lib for frontend

help

Options:
      --include-mode <INCLUDE_MODE>
          Which operations to include
          
          [default: only-public]

          Possible values:
          - only-public:       Only public options
          - public-and-hidden: Both public operations and operations marked with `x-hidden`
          - only-hidden:       Only operations marked with `x-hidden`

[svix-james]

I get it, but PublicAndHidden just kinda makes my brain bleed blood tears when I read it.