[io] Properly handle failures in custom streamers

[silverweed]

Explain what you would like to see improved and how.

Currently custom streamers have no reliable way to communicate failure to the calling code (e.g. to have it skip the current object). A possible way to add this capability would be through exceptions, but the I/O code must be made exception safe and properly handle the exceptions if that is the way we wanna go.

ROOT version

6.33.01

Installation method

from source

Operating system

Linux

Additional context

RNTuple::Streamer currently uses exceptions to communicate failure, but this is not necessarily handled corrently in the calling code right now.

[hahnjo]

Hm, I may have actually addressed this with https://github.com/root-project/root/pull/19386 (to some degree)