[DF] Add test for ROOT-10792, Snapshot of TClonesArrays
[DF] Add test for ROOT-10792, Snapshot of TClonesArrays

The test is incomplete: it covers
`Snapshot<TClonesArray>(..., {"tclonesarray"})` and
`Snapshot(..., {"tclonesarray"})` but it currently does not cover
`Snapshot<RVec<T>>(..., {"tclonesarray"})` because I have to figure
out how to generate dictionaries for google tests without race
conditions in the build system.

olifre/root,olifre/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,root-mirror/root,olifre/root,olifre/root,olifre/root,karies/root,karies/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root