Support maintenance window for module upgrades

[pbochynski]

Description
Requirements:

• possibility to mark versions that require a maintenance window
• possibility to assign clusters to maintenance windows (maintenance windows can be different for regions, customers, etc)

Modules should still be reconciled to make sure that the Manifest is healthy, given module upgrades should happen ONLY during the maintenance window.

Reasons

Some module upgrades can come with service disruption that should be handled within the maintenance window.

Implementation Concept

• Module version should get additional attribute (requires downtime)
• Maintenance windows should be assigned to the landscape, region, or individual Kyma instance (maybe annotation in the Kyma CR in KCP)
• KLM should respect maintenance widows
• The user should be able to override the default maintenance window (annotating Kyma CR in the cluster)

Acceptance Criteria

• Describe the Maintenance Window behaviour
  • Given a Kyma Module in the Kyma Module Catalogue
    • When a new Kyma Module version is added to the Kyma Module Catalogue
      • Then an entry in Module Catalogue is updated
        • And the Kyma Module entry contains information whether a new version of Kyma Module should be upgraded during the Maintenance Window
    • When the Lifecycle Manager reconciles Kyma Module
      • And the new version of the Kyma Module is available and requires a Maintenance Window
        • And the Maintenance Window is currently active
          • Then the Kyma Module is upgraded to the new version
        • And the Maintenance Window is currently not active
          • Then the Kyma Module is not upgraded and reconciled in the current version until the Maintenance Window is active
        • ❓ And the User chose to ignore maintenance window
          • Then the Kyma Module is upgraded to the new version

[janmedrek]

Multiple versions of the modules will be introduced in this epic: kyma-project/lifecycle-manager#1472

Until then, there is no persistence of multiple module version and thus, this ticket is blocked.

[jeremyharisch]

Acceptance Criteria for EPIC:

• Research about the topic
• Think about a proper issue split for this EPIC
• Create Sub-Issues to cover the implementation
• Regarding business requirements talk to @janmedrek if needed

Timebox: 2 Days