FindMatlab: Restore support for versions without VersionInfo.xml
Report "unknown" in _Matlab_VersionInfoXML
if file is missing.
Fix omitted MATLAB root with unknown version from XML.
I increased the nesting level of the function to match the existing style of this function. This function could be refactored to using 'if guards' with early returns to reduce the complexity in another MR if desired.
Fixes: #25585 (closed)
Fixes: #25586 (closed)
Backport: release
Topic-rename: FindMatlab-fix-version-without-versioninfoxml
Edited by Brad King