Merge branch 'feature/csp_mastofe-dev' into 'develop'

Add CSP for mastofe development, remove secure-cookies in MIX_ENV=dev

See merge request pleroma/pleroma!820
2 jobs for bugfix/mdii-uploader in 6 minutes and 58 seconds (queued for 1 second)
Status Job ID Name Coverage
  Lint
passed #16807
lint

00:02:44

 
  Test
passed #16808
unit-testing

00:04:13