Simplify display of features in technical preview to easily identify them and their current state

User story:

• As a user I need to be able to see all Technical preview features on PMM setting page so I can On /OFF them when it's needed, not only when the container is started
• As a PMM user, I need to be able clearly to see what FEatures in PMM are in tech preview before I've turned them On on the Settings page 
• As a PMM user When I'm on the page related to the feature in Technical preview  -  I need to be able to see  some information about this feature being in tech preview, so I can understand what level of stability it provides  

UI/UX: 

TBD

Dfart: 

Acceptance criteria

• User able turn On/OFF any feature flag  over UI or passing env variable during the docker start 
• User can clearly see the Tech Preview features and get information about  "What does Tech Preview means" = https://www.percona.com/doc/percona-monitoring-and-management/2.x/details/glossary.html#technical-preview
• "Notification " on pages - related to features in Tech preview ( ? ) 
• Documentation

• • Separate location (page/section) to explain differences between GA and Technical Preview features
  • All Tech. Preview features linked to this  location   

Out of scope:

Suggested implementation:
TBD

How to test:
TBD

Details:

• Alerting need to be NOT in Tech preview