Automation for subscribing PMM Server to the platform

User story:

As an SRE I want a mechanism to automate my PMM fleet deployment and get them subscribed to the Percona Platform so that I don't need to pull/ask for new tokens every time automation runs. These deployments can happen at any time and without human intervention. 

Acceptance criteria:

• I have a mechanism to subscribe PMM to PP
• my automation code/configuration doesn't need any code change or user intervention unless the admin decides to
• An admin user can take action to stop this, i.e. manually rotating a token.
• This mechanism is fully documented

Details:

Right now a token can be used but

• these tokens are for individual users
• It's valid for only 30 mins
• if the individual login again it gets rotated

All these make me impossible to automate deployments without human intervention and without having an admin account in the Percona Platform.

I recommend having an organization's token without TTL that can be rotated only by admin users.