Document product integration for adding CI tests

Details:

• Dependencies installation
• Test values overview
• Enabling of "internal" database, storage, etc for testing
• Cypress test creation and running in pipeline
• Shell script creation and running in pipeline
• References to good examples
• Minimum set of tests to "smoke test" package (e.g. account creation, database store/retrieve, admin/user login, etc.)

If any of this is already documented, provide references to that documentation rather than repeating.

NOTES:

• Use PodInfo as the example app in all instructions. We want someone following the documents from beginning to end able to add podinfo into Big Bang.
• Placeholders for docs will be created in this MR. Format is markdown.
• Any overlapping sections in the original package integration doc should be cleaned up with references to this doc. The original may be renamed to package-integration-supported.md.