Fix/test orphan check script squash

• Added git remote prune origin and git fetch --prune for sdk and each submodule to ensure there is no tracking of remote stale branches.
• Now fails if any submodule first commit is orphan, instead of checking just the last submodule (submodules shells are communicating exit code through 'exit_code_file'
• Checked that there is no false positive nor false negative by creating 2 dummy branches in msaaudio and ms2, committed 2 times, then merged dummyBrach2 in dummyBranch with squash and branch delete, without updating submodules in sdk
• Fixed little typo in error message