call setIntroducer() when setting up a provider via invite code

while !308 (merged) added the required UI to set an introducer, the actual call to bitmask-core is still missing.

This depends on #9185 (closed)

changed milestone to %2025.02 LEAP VPN Release

implemented in !311 (closed)

mentioned in merge request !311 (closed)

assigned to @cyberta

closed

!311 (closed) was closed in favor of !324 (merged)