server sided external api calls (#697)

* server sided external api calls

* fix uploading gpx files

* rename api/v1/nominatim with api/v1/geocoding to prepare photon support

* remove NOMINATIM_MAX_RETRIES (side-kick from other PR)

* re-add nominatim url fallback

* docu, env var defaults and fallbacks, docker compose files

* refactor

* furhter refactorings and fixes

* PUBLIC_VALHALLA_ENABLED in docker compose files added

* fix env var names

---------

Co-authored-by: Flomp <Flomp@users.noreply.github.com>

web/src/lib/server/http.ts

@@ -0,0 +1,18 @@
+import { json } from "@sveltejs/kit";
+
+function safeJson(text: string): any {
+    try {
+        return JSON.parse(text);
+    } catch {
+        return { message: text };
+    }
+}
+
+export async function proxyJsonResponse(response: Response) {
+    const text = await response.text();
+    const payload = text.length ? safeJson(text) : {};
+    if (!response.ok) {
+        return json(payload, { status: response.status });
+    }
+    return json(payload);
+}