CMake ExternalProject: add `TIMEOUT`

[Axel-Naumann]

Explain what you would like to see improved

We had CI builds stuck in downloading dependencies, e.g. VecCore. That should timeout.

Optional: share how it could be improved

Add the TIMEOUT parameter to all ExternalProject calls downloading sources.

[Axel-Naumann]

Check the CMake TIMEOUT parameter for ExternalProject. Not sure what else to add. If this is unclear for you then maybe pick a different issue to start with?

[harshal0815]

@Axel-Naumann @oshadura Pull Request : #7141

[oshadura]

fixed in: #7141