[rfile] Allow setting object titles when writing

[silverweed]

This Pull request:

Adds the ability of storing object titles when writing objects to RFile.

CAVEATS/to be discussed:

• TObjects are not treated specially, meaning that if your TObject has a title it won't be used automatically when storing the object (for that you need an explicit rfile->Put("obj", obj, obj->GetTitle()));
• Doing a rfile->Put("obj", myTObject, "My Title") will not set myTObject's title, but only its key's. This means that this potentially unexpected behavior will occur:

rfile->Put("myobj", myobj, "obj title");
auto myobj2 = rfile->Get<MyTObj>("myobj");
cout << myobj2->GetTitle() << "\n";  // prints ""

In order to retrieve the object's title you'd need to do it from the key:

auto keyInfo = rfile->GetKeyInfo("myobj").value();
cout << keyInfo.GetTitle() << "\n"; // prints "obj title"

To be discussed: are we ok with this behavior or do we want bespoke TObject/TNamed code in the implementation to mitigate these pitfalls?

[github-actions]

Test Results

    22 files      22 suites   3d 14h 48m 1s ⏱️
 3 873 tests  3 817 ✅ 0 💤 56 ❌
76 034 runs  75 977 ✅ 1 💤 56 ❌

For more details on these failures, see this check.

Results for commit 4741af9.

♻️ This comment has been updated with latest results.