Connect PMM Server to Percona Portal for additional account info in PMM and value added content

As a PMM admin/Portal Org Admin, I want to be able to connect my PMM server (from within PMM) to Percona Platform.

Context

One of the key features in Platform Portal version 1 is to allow users to connect their PMM servers to the Platform. By doing so, Percona will be able to leverage smart advisors (and, in the future, more intelligence), thus adding an important value to users/customers. To do so, Platform needs to offer an API that allows PMM instances to register themselves with Platform.

Tech Specs / UI UX

Detailed tech specs and UI/UX design can be found at https://confluence.percona.com/display/PMM/Single+Sign-On+-+PMM+Server+integration+with+Portal+and+Okta#SingleSignOnPMMServerintegrationwithPortalandOkta-ConnectPMMServertoPortal

Acceptance criteria

• It is possible for admin users in PMM to access a Percona Platform section under PMM settings

• This section will offer a form that allows the user to connect the PMM instance to Percona Platform

• The user must enter the PMM server name, and the credentials corresponding to her/his Percona Account

• After submitting the form with valid data, the PMM instance should now be connected to Percona Platform

• If the user signs in to Percona Platform and navigates to the list of connected PMM instances, the user should be able to see the newly connected PMM server  ( : moving this to separate issue )

• In PMM, the user should now clearly see that the PMM instance is connected to Percona Platform

• The old way of auth is replaced - SessionID is replaced by the access_token we get from Okta directlly.