Refactor permission queries to joins

[ZakarFin]

On local dev with some 3000 layers. Loading layers from db (with heavy logging so it's not properly measured):

Before:

• Amount of select queries for permissions: 6097
• Timing between selected log entries: 11,6s
• Layerlist response for browser without SQL logging: 4,2s

After:

• Amount of select queries for permissions: 15
• Timing between selected log entries: 3,9s
• Layerlist response for browser without SQL logging: 3,6s

Time measured from log entries between:

• from "GetAppSetupHandler - View ID: 1 created by user -1 is public, access granted for user with id -1 "
• to "OskariLayerWorker - Returning 2712 / 2928 layers "
  So this includes loading the whole layer list and some other stuff, but with all the sql logging happening which I'm sure adds a lot to it.

In addition, change to OskariLayerWorker to fetch permissions for individual layers instead of full set improved GetAppSetup performance from 2-5seconds down to ~60ms

[jampukka]

Looks good