feat: use only one identity provider

Additionally remove ionic-appauth dependency,
refactor the relevant code and fix some issues.

Closes #245

frontend/app/package.json

@@ -81,7 +81,7 @@
     "@maplibre/ngx-maplibre-gl": "22.1.0",
     "@ngx-translate/core": "15.0.0",
     "@ngx-translate/http-loader": "8.0.0",
-    "@openid/appauth": "1.3.2",
+    "@openid/appauth": "1.4.0",
     "@openstapps/api": "workspace:*",
     "@openstapps/collection-utils": "workspace:*",
     "@openstapps/core": "workspace:*",
@@ -93,7 +93,6 @@
     "deepmerge": "4.3.1",
     "form-data": "4.0.6",
     "geojson": "0.5.0",
-    "ionic-appauth": "2.1.0",
     "ionicons": "8.1.0",
     "jsonpath-plus": "10.3.0",
     "maplibre-gl": "6.4.1",