Allow some notebook cells to run before auto-injected preamble

[ilia-db]

Currently we inject special code into notebooks before we execute them as workflows.

If some later cell execution leads to a kernel restart, then our injected code is no longer takes effect.

We already support %pip commands (that lead to kernel restarts) in any cell by executing them before our injected code (more info in this isue and this PR)

Here we want to execute a full cell before our preamble.