Add OCM Test Suite matrix workflow for CERNBox

[MahdiBaghbani]

This PR is a part of cs3org/OCM-STA#3
This PR is a part of cs3org/OCM-STA#4

The document for this workflow can be found on OCM Test Suite

A demo of the run can be found in the GitHub Actions, you can also download and review the videos generated by Cypress from artifact section.

This pull request adds a dedicated GitHub Actions workflow that runs the OCM Test Suite against CERNBox and Reva using a small, fixed invite link matrix.

• The workflow builds and uploads a static revad binary from the current branch, then uses that binary inside the CERNBox containers.
• A single matrix actor job runs four invite link combinations:
  • Stub v1.1.0 <-> Stub v1.1.0
  • Stub v1.1.0 <-> CERNBox (current Reva build)
  • CERNBox (current Reva build) <-> Stub v1.1.0
  • CERNBox (current Reva build) <-> CERNBox (current Reva build)
• Each matrix entry prepares a small dev stock root, pulls the required Docker images, mounts the Docker socket, and runs the OCM Test Suite via the dev stock image with scenario invite link.
• When a combination needs the current Reva code, the workflow downloads the revad binary artifact into a host directory and passes it into the dev stock container via REVA_BINARY_DIR.
• A summary job reads one row JSON status artifacts for each combination, writes a compact Markdown table into the GitHub Actions summary, and then deletes the status artifacts while keeping the revad binary and all Cypress videos and screenshots.
• The matrix job is configured as non blocking with continue on error, so all four combinations are attempted and OCM regressions are reported without failing the entire CI run.

This gives CERNBox and Reva a clear, repeatable invite link compatibility check between Stub and the current Reva build.

The OCM-Stub is subject to be developed in the next milestone, and this workflow would also be updated, as of now it is expected that the results for the CERNBox to Stub and Stub to CERNBox to be failure.

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.