gRPC: increase max message size from 4 MB to 10 MB
gRPC: increase max message size from 4 MB to 10 MB

individual scanned pages (used in a Convert RPC) come in at about 5-6 MB

stapelberg/scan2drive,stapelberg/scan2drive,stapelberg/scan2drive,stapelberg/scan2drive,stapelberg/scan2drive