The plugin docs show yaegi plugins reading Vikunja configuration via
pkg/config and github.com/spf13/viper, but neither package was registered
in the yaegi symbol table. Plugins importing them failed to load at the
import itself.
Add both packages to yaegiSymbolPackages and commit the generated symbol
files so interpreted plugins can read configuration as documented.
Fixes#3500.
Nick Manosandkolaente
358d043fb9