[Quickstart] Add Support for Quickstart To Cater SDK Quickstart and Portal Quickstart

[aliasghar98]

What

The apimatic portal quickstart command needs to be removed and will be added under the umbrella of apimatic quickstart in order to add support for a quickstart flow that allows a user to get started with either SDK(s) or Portal.

Why

We need to provide a user flow where a user can easily discover and get started with SDK(s) or a Portal.

User Flow

[aliasghar98]

Discussion Points:

• For SDK-specific users, we will be going with approach 2.
• Update portal generate message to run apimatic quickstart with portal selection in case it's not a valid src directory.
• Update next steps with onboarding points i.e. languages.
• Expectation: Run quickstart once -> then the portal/sdk generate command. Construct the command for copy+paste in the next steps section.
• Update quickstart commands to display a message that they're not built for CI/CD flows.