Suggestion: Move imports to local scope

[zain-sohail]

Due to how the current interface works, all possible dependencies are imported when importing SedProcessor from sed.

I propose we remove the linter for module level imports and import them in scope when necessary. This will reduce first time importing time from ~30 s to something more managable.

[rettigl]

For me, it takes typically 10s max to load. As anyways all calibrators are loaded with the processor, I don't see that we would gain much.