Add new command line option to skip user input

Currently if TOSCA template requires 'input parameters' then when user is required to provide those inputs when run translator. There are certain cases when user may not want to provide it. For example, the inputs are specific to Heat and user want to provide it when run translated template OR when user is only interested in validating the template (e..g with ongoing Murano work where a validation of template is required)
We need to create an option something like ' -- ignore_input true'

A new option '--validate' is planned to create under,
https://blueprints.launchpad.net/heat-translator/+spec/tosca-cli-validator

Once that work is done --validate should implied that ignore_input is set to true.