Right now only env and vars are templated. However it is a common scenario to template some others (like the --full-refresh flag).

This PR does:

• Split global and command specific params/flags/args
  dbt [GLOBAL PARAMS] <COMMAND> [COMMAND PARAMS]
• Render the command programatically. Using an easily modifiable TypedDict It's not required to add params to the render function anymore. You would want to:
  1. Add your new flag/param to the corresponding TypedDict in dbt_command_params.py.
  2. Add the param to the DbtBaseOperator constructor
  3. Add te param to the constructor body, where it gets assigned to the right block
• Fix the testing

Fixed issues:

• Close DbtRunOperator cannot be run in debug mode #61: it implements the debug flag
• Close Add DbtSourceFreshnessOperator #59: you can instantiate your own DbtBaseOperator(command='source freshness')
• Closes Add models to template fields #46: it implements param
• Close Use --no-use-colors in dbt_hook.py #43: the render function supports negative flags
• Close Adding full_refresh to template fields #30: --full-refresh is now templated