Improve resource state overview in SKR

[dushanpantic]

Description

The user should be able to see the state of their resource in the SKR.

Currently, we have the following states:

• Processing
• Creating - state after resource is applied, triggered in SKR
• Deleting - state after resource is deleted, triggered in SKR
• Ready - this state is propagated from the KCP
• Error - this state can be either propagated from KCP or triggered in SKR due to invalid resource

Problem - missing states
There are also cloud-provider specific states like Maintenance, Repairing, FailingOver, etc., that would be nice to have, but probably impossible to sync due to the reconciliation period. We can leave them out of the picture, for now.

The main state that is lacking from the list above, is Updating. Updating is a lengthy operation, and, for the sake of UX, it must be shown to the user.
But this brings us to the next problem: while the update is happening, depending on the update type, the instance may or may not be available. If we just show Updating, user won't be able to know if the instance is ready or not

Problem - separating resource readiness from resource state

To solve the problem above, we could use what @ravi-shankar-sap mentioned in the yesterday's meeting: separation of readiness from the state. That would bring us to the following:
Readiness:

• Ready
• Not Ready

State (resource can only have one state at the time)

• Error
• Creating
• Updating
• Deleting
• ...

Problem - unified implementation
As all resources can have multiple conditions at any time, perhaps those conditions can be evaluated to provide resource readiness and state.
This should be an open discussion, so please leave your ideas in the comments below.

Reasons

The main reason for this feature is UX.