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/api/cookies.ts

@@ -0,0 +1,33 @@
+export function parseCookies(cookieHeader: string | null) {
+  const cookies: Record<string, string> = {};
+
+  if (!cookieHeader) {
+    return cookies;
+  }
+
+  // Split the cookie string by semicolons and spaces
+  const items = cookieHeader.split(';').map((cookie) => cookie.trim());
+
+  items.forEach((item) => {
+    const [name, ...rest] = item.split('=');
+
+    if (name && rest.length > 0) {
+      // Decode the name and value, and join value parts in case it contains '='
+      const decodedName = decodeURIComponent(name.trim());
+      const decodedValue = decodeURIComponent(rest.join('=').trim());
+      cookies[decodedName] = decodedValue;
+    }
+  });
+
+  return cookies;
+}
+
+export function getApiKeysFromCookie(cookieHeader: string | null): Record<string, string> {
+  const cookies = parseCookies(cookieHeader);
+  return cookies.apiKeys ? JSON.parse(cookies.apiKeys) : {};
+}
+
+export function getProviderSettingsFromCookie(cookieHeader: string | null): Record<string, any> {
+  const cookies = parseCookies(cookieHeader);
+  return cookies.providers ? JSON.parse(cookies.providers) : {};
+}