Add HasChanges() to Snapshot<T> for efficient change detection

[joatansampaio]

Currently, Snapshot exposes Changes() and UpdatedColumns(), but there’s no direct way to check if any changes exist without calling Changes().Count > 0 or Changes().Any().

• This PR adds a convenience method HasChanges() with an early-exit loop to Snapshot that improves code readability and avoids unnecessary allocation of a List when only a boolean check is needed.

Example

Before:

if (snapshot.Changes().Count > 0) // Or .Changes().Any()
{
    db.Update(obj, snapshot.UpdatedColumns());
}

After:

if (snapshot.HasChanges())
{
    db.Update(obj, snapshot.UpdatedColumns());
}

#Tests
Added unit tests in SnapshotTests verifying:

• HasChanges returns false when no changes are made.
• HasChanges returns true when tracked object values are updated.
• HasChanges reutrns the same as Changes().Any()