Implement GF plugin translations workflow

Summary

Based on the investigation that concluded in PLANET-6971 we can implement the steps involved to use LoCo for NROs to be able to translate form strings.

Requirements

• Copy and add all gravity forms language files in master-theme repo under /languages/plugin/ folder. (We will keep all other 3rd party plugins translations files in same folder.)
• Add a post deploy script which copy language files from master theme /languages/plugin/ to wp core-> /languages/plugins/.
• The Gravity forms, translation found to edit at here in Loco Translate plugin.
• On click of "Save" button in Loco Translate plugin's Gravity forms translation, sync the translation in master-theme. (Commit translations files to master theme in same way we do for master-theme translation.)