[cmake][ci] Test hub as submodule

[hiergaut]

Pull Request Desription

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Please check if the PR fulfills these requirements

• The commit message follows our guidelines (see CONTRIBUTING)
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Be aware that the PR request cannot be accepted if it doesn't pass the Continuous Integration tests.

• What kind of change does this PR introduce?

  • bug fix
  • feature
  • docs update
  • other: CI

• What is the current behavior? (You can also link to an open issue here)
  Not check performed for project using hub as submodule.

• What is the new behavior (if this is a feature change)?
  Check hub project as submodule using gh-testAsSubmodule branch

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• Other information:

[hiergaut]

Will uncomment when rebase from #39 and #49.