[POC] Command to deploy kyma modules

[kwiatekus]

Description

• kyma (alpha) add - when no specific modules are provided, install default modules (right now istio, api-gateway, btp-operator) with default configuration
• kyma (alpha) add -m serverless telemetry - install serverless and telemetry (only) with default configuration
• kyma (alpha) add -m serverless:1.2.1 telemetry nats eventing - install modules in the version from regular channel, but serverless in the specific 1.2.1 version
• kyma (alpha) add -m serverless --customCR={path to yaml} - install serverless without applying default configuration
• kyma (apha) remove -m serverless - remove counterpart that should remove all resources accoridng to the module manifests.

The commands should install operators in kyma-system namespace. It should ensure that the namespace exists (create if needed). If user already has the module but in older version we will install it from latest

This commands allow to install modules in a managed and non managed clusters. Installing module like that does not make it "managed", that is: the lifecycle of the module operator is not managed externally (not added to Kyma CR, not following release channel)
Those commands require source of truth regarding known modules and their git repositories (module catalog)
(here is an example from Piotr's POC)

Until we have a final module catalog we can use this one: https://raw.githubusercontent.com/kyma-project/community-modules/main/model.json

Do not call github api to fetch additional module info (i.e all versions). Rely on module metadata offered in module catalog.

Reason

We need to help users to manage installed modules in a streamlined way. Currently all kyma modules explain how to install them (i.e here) but we are in need for a CLI tool that would realise that in an unified way. Currently supported commands (deprecated) do not realise the installation in a modular fashion:

• current kyma deploy doesnt install kyma modules but uses previous installer mechanism and reconciler code.
• current kyma alpha deploy instals lifecycle manager which is something that neither OSS kyma users nor managed kyma runtime users would like to do.

Related
kyma-project/community#872 (comment)