Export to Carbon: parametrize cli

[miguelangel-dev]

Using the parametrized carbon's script nef-carbon-page done in this PR #57. In this issue, we will connect to nef to expose this functionality from CLI:

Example of use

nef carbon --project . --output ~/Desktop <params optionals>

where <params optionals> are:
--background - this is the background color
--theme
--size - export file size
--font - font type
--lines - show/or not the lines in the exported code snippet.
--watermark - show/or not the watermark in the exported code snippet.