places: show the community's published pictures first in Pick a picture

The service delivers the pictures review approved for a place, but TREK never
read them. A new TrekCommunityService in the maps domain asks the TREK Places
API for them (the index row for a gers place, /v1/community for an OSM one),
accepts only paths of the service's picture store, and fetches the bytes with
the installation's key, capped at 4 MB. Enrichment puts them ahead of Google
and Commons, through the same photo cache, credited as TREK Community under
CC BY 4.0. The enrichment cache now follows the community version for OSM
places too, so a newly approved picture shows on the next open.

Also lowers the client's no-non-null-assertion baseline to 380: moving Use
this text into the description card removed two.

client/scripts/eslint-baseline.json

@@ -1,6 +1,6 @@
 {
   "src": {
-    "@typescript-eslint/no-non-null-assertion": 382,
+    "@typescript-eslint/no-non-null-assertion": 380,
     "@typescript-eslint/no-misused-promises": 847,
     "no-console": 88,
     "complexity": 218,