add storyblok path to migration

[Markvandersteen]

In de cli we want to be able to run a migration agains a path in storyblok.
example:

we have a path groupwebsite-dpl

And we want to run a migration only in that folder.

Suggestion:

storyblok run-migration --space xxxxx --component COMPONENT --field FIELD --storyblok-folder ./groupwebsite-dpl

We host multiple websites in a single space and this would make our migrations much more saver and efficient since currently we have to run the migration against the entire space which cost time and invites more risk to the migration.