Rework spoolmanager as a plugin

[Rock Storm]

Currently spoolmanager does not properly track used filament, only accounts for full prints. Plus it was implemented as an appendix, which is not modular nor reusable. The appropriate approach would be to (re)implement it as a plugin so the filament amount is updated on every single extrusion action regardless of whether it occurs in a print or not.

Such rework can include suggestions like #1059.