[TDF] Fix ROOT-8979: write c-style arrays with Snapshot
[TDF] Fix ROOT-8979: write c-style arrays with Snapshot

The fix relies on:
- users only ever using `array_view<T>` in `Define`, `Filter` and TDF
  actions to read c-style arrays from TTrees, and not for std::vector,
  for example
- the fact that for TTree branches that contain c-style arrays one can
  use the title of the input branch as the title of the output branch,
  as is

The fix requires to `const_cast` away the constess of the pointer
returned by `array_view::data` to pass it to `TTree::Branch`.
Because of this last issue and because of the first point above,
in the future it might be better to not use `array_view` but our
own custom type `TDFArray` to let users signal c-style arrays.

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