Save reliability improvements

This release resolves issues with failed saves. We have restructured the logic for saving files in the content and visual editors. This should be more reliable and recover from failed saves better.

Features:

• Save progress shown during Uploading Changes step
• Hugo updated to 0.89.4
• Added support for Node.js 16.x and made Node.js 16.x and npm 8.x the default versions. To stay on Node.js 14.x you can add a .nvmrc file to the site and run nvm use (or simply run nvm use 14) in the build hooks

Fixes:

• Better save and save-failure logic
• Default content files with editor types are preferred
• Fixed issue with the build process not copying files starting with a dot
• Fixed issue setting global _inputs settings for Hugo