Create a basic operator

[siegfriedweber]

The operator should be able to deploy a working OpenSearch instance where all necessary configurations can be done via overrides.

A smoke test should be provided.

The operator may use the official OpenSearch image as long as the image from Stackable is not yet created.

Part of #1

Tasks

• Fix the deployment via Helm #3
• Decision: Mapping of OpenSearch node types to roles #8
• Basic operator #10
• feat: Add OpenSearch operator ci#136
• feat: Add OpenSearch to the README file operator-templating#541
• feat: Add the product "opensearch" stackable-cockpit#400
• chore: Release stackablectl 1.1.0 stackable-cockpit#401
• test: Disable memory mapping #11
• feat: Add the opensearch-operator to the dev release release#37
• Add opensearch-operator documentation#758
• Add OpenSearch documentation-ui#135
• Add opensearch-operator crddocs#51
• [IN PROGRESS] Document the operator, especially the config overrides
• Revise the code (e.g. add comments and fix TODOs)