deprecation and removal of impulse project

[jurgenvinju]

This is to register the intent to mark the "impulse" project for deprecation and eventual removal.

• only rascal-eclipse depends on impulse and this is to be marked for deprecation and removal as well.
• it seems we have no outside customers for impulse who we could damage, also impulse runtime is hosted at the impulse generation still for archival purposes
• by removing such code we improve the general sustainability of what is left
• we have to wait at least a year from this day (Feb 2nd, 2023) to give users time to migrate to VScode

Please vote here for consent:

• @jurgenvinju
• @tvdstorm
• @PaulKlint
• @DavyLandman

The "project burial process" is described here. We can add more details as we go, as this is the first project we clean up after: https://usethesource.io/about/processes.html#:~:text=Project%20Burial%20Process