Fix some refactiring error. And Add a way to insert admin credentials

lib/peertubeRequester.ts

@@ -27,21 +27,21 @@ class PeerTubeRequester {
     this.password = config.password;
   }
 
-  private async requestAuthToken(): Promise<any> {
+  async requestAuthToken(): Promise<any> {
     let response = await fetch(
       new URL(`/api/v1/oauth-clients/local`, this.domainName)
     );
     if (!response.ok) {
-      throw new Error(response.statusText); // CRASH
+      throw new Error("Cannot get client credentials : " + response.statusText); // CRASH
     }
     const { client_id: clientId, client_secret: clientSecret } =
       await response.json();
 
     const clientInfo: { [key: string]: string } = {
-      clientId,
-      clientSecret,
-      grantType: "password",
-      responseType: "code",
+      client_id: clientId,
+      client_secret: clientSecret,
+      grant_type: "password",
+      response_type: "code",
       username: this.username,
       password: this.password,
     };
@@ -54,7 +54,7 @@ class PeerTubeRequester {
       body: myParams,
     });
     if (!response.ok) {
-      throw new Error(response.statusText); // CRASH
+      throw new Error("Cannot get access Token : " + response.statusText); // CRASH
     }
     const { access_token: accessToken } = await response.json();
     return accessToken;