[ntuple] Fixes for alignment

[jblomer]

Use the new TClass alignment information where applicable. This fixes

• Alignment of classes whose alignment is defined by a transient member
• Alignment of certain streamer fields

Additionally, use the new and delete operators with alignment info. This ensures correct memory allocation for over-aligned types.

Fixes #16765

[github-actions]

Test Results

    22 files      22 suites   3d 14h 33m 49s ⏱️
 3 859 tests  3 856 ✅   0 💤 3 ❌
76 253 runs  76 145 ✅ 105 💤 3 ❌

For more details on these failures, see this check.

Results for commit 39576f7.

♻️ This comment has been updated with latest results.

[hahnjo]

The code changes look good overall; quickly looking at the failures, it appears that macOS and Windows are complaining about the missing import of <array>. Not sure if that solves all issues...

[hahnjo]

As discussed offline, this is missing the part of aligning the dynamic array in std::vector<T> (relatively easy to do) and RVec<T> (harder because it currently uses malloc and free). In the worst case, we discussed throwing in case we have alignment larger than std::max_align_t

[pcanal]

LGTM. Thanks.

[hahnjo]

Looks good in principle. Windows is unhappy, which I think is because of aligned operator new in the header / just-in-time-compiled code. Maybe this can be solved by outlining the function?