Avoid copying of note's metadata in getter

[polydez]

Let user of the getter decide, if they need to copy it.

[bobbinth]

Looks good! Thank you!

Is this critical for the node? If so, we should merge this into main and I can make another release (e.g., v0.2.1). If not, we can merge this into next and use it in the next version of the node (i.e., v0.3).

[polydez]

Is this critical for the node? If so, we should merge this into main and I can make another release (e.g., v0.2.1). If not, we can merge this into next and use it in the next version of the node (i.e., v0.3).

It's not critical, I've added TODO in order to simplify code later:

// TODO: Substitute by using just note.metadata() once this getter returns reference
//       Tracking PR: https://github.com/0xPolygonMiden/miden-base/pull/593
match note {
    OutputNote::Public(note) => note.metadata(),
    OutputNote::Private(note) => note.metadata(),
},