Add an in memory credential providers

[mbenita-Cyberark]

Is your feature request related to a problem? Please describe.

Currently we have two keystore for the CLI and Client. these are Keystore and FileCredentialProvider.
While working with the Cli these are two sufficient solutions. The SDK can use a better and more secure Provider, which is a simply in memory credential provider. which holds the api-key and the rest of credentials data in memory for as long as the app running

Describe the solution you would like

Create a simple CredentialProvider implementing CredentialsStoreInterface.
The Client should accept CredentialsStoreInterface instance as a parameter. this way the user can decide which CredentialProvider to use.
This means we need to expose our factory method outside as well. so the user could inject the right instance

Describe alternatives you have considered

Additional context

Add any other context information about the feature request here.

[sigalsax]

I like the idea! I feel though that I do not have enough information to properly evaluate. The issue/design would greatly benefit from pseudocode / flow diagrams so that the reader can fully capture your vision and form an opinion.

How should the client be updated? What are the consequences of this change? How do you plan to account for backwards compatibility (if necessary), why is memory safer than a cred store for example? Should we also provide this in option for the CLI? These are all points that should be touched on.

[oburstein-hub]

A direction of extracting a common interface for all types of CredentialProvider sounds a good direction to me.
The only question is if all the methods (APIs) of these Providers look then same
If they are - there is no problem to extract this interface

[mbenita-Cyberark]

We Allready have this interface.. So basically you are favor for this idea.
@sigalsax gave some very important insights. I'll open a small PR that will address those insights.