Add a `--skip-npm` like option

[simonihmig]

It would be nice if we could skip installing dependencies after the migration

• when things are not in the right shape yet (like when working on the migrator itself)
• when working on large monorepos, that take a long time to install. Especially when some post-install scripts (turbo, nx) kick off automatically

Probably that means we also have to skip lint:fix, but that's fine.

[NullVoxPopuli]

Likely blocked by: https://github.com/ember-cli/ember-cli/pull/10216

[simonihmig]

Right... and... oh wow! You have already started working on this, this is awesome! 😍