Simplified UI for email-senders

Ref #682

List of changes:

• remove warming replies from returned (blocker, to be done in a follow up MR)
• remove alert: Automatic blocking of SMTP & IMAP attacks disabled
• placeholder in the graph
• explain message statuses (message detective?)
• settings page - remove link from the top ?
• remove walkthrough?
• privacy policy new link: https://lightmeter.io/privacy-policy-delivery/
• remove settings link from message detective page (maybe include here statuses explanation)
• remove info button
• bottom thank you link -> link to getlightmeter
• info: click esc to exit graph
• message detective as text on top menu link rather than icon (magnifier)
• remove feedback buttons

This With the simpleViewEnable feature flag enabled, controlcenter now looks like that: