Implement Feature-Policy header

Article: https://scotthelme.co.uk/a-new-security-header-feature-policy/
Ref: https://securityheaders.com/?q=https%3A%2F%2Fdemo.phpmyadmin.net%2FQA_5_0%2F&hide=on&followRedirects=on

cc @emanuelb If you have some feedback on this implementation

Target branch: master