[ntuple] Allow for creating bare model from on-disk info

[jblomer]

Explain what you would like to see improved and how.

Currently, RNTupleDescriptor::CreateModel() always creates a full model with a default entry. There can be situations in which a bare model is preferable.

ROOT version

master

Installation method

n/a

Operating system

n/a

Additional context

No response

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[github-actions]

Hi @silverweed, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖