tech: Remove inline CSS usage

[pnu-s]

A couple of changes in order to remove inline CSS usage and improve CSP headers.

I made the changes in separate commit in order to make it more readable, but here is what I did in more details:

• Add django-csp in local dev only in order to have CSP headers locally for testing purposes
• Remove all inline CSS
• Prevent ajax call if the handle is empty (currently there is a bug if you start a search without handle on the homepage)
• Remove "Refresh" debug log line
• Fix a couple of indentation issues

After releasing this, we'll be able to make the following changes to the CSP headers in production:

• change default-src from 'self' to 'none'
• add connect-src with 'self'
• change style-src from 'self' 'unsafe-inline' 'unsafe-eval' to 'self'

About the CSP, we still need to get rid of unsafe-eval for JS, I'll make a separate PR with this.
There are more indentation issues but I didn't want to clutter the PR even more. I'll make a separate PR.

[U039b]

Thank you very much! It looks good to me :)