feat: configure dynamic providers via .env (#1108)

* Use backend API route to fetch dynamic models

# Conflicts:
#	app/components/chat/BaseChat.tsx

* Override ApiKeys if provided in frontend

* Remove obsolete artifact

* Transport api keys from client to server in header

* Cache static provider information

* Restore reading provider settings from cookie

* Reload only a single provider on api key change

* Transport apiKeys and providerSettings via cookies.

While doing this, introduce a simple helper function for cookies

app/lib/modules/llm/manager.ts

@@ -83,7 +83,7 @@ export class LLMManager {
 
     let enabledProviders = Array.from(this._providers.values()).map((p) => p.name);
 
-    if (providerSettings) {
+    if (providerSettings && Object.keys(providerSettings).length > 0) {
       enabledProviders = enabledProviders.filter((p) => providerSettings[p].enabled);
     }