squash! PATCH: Authenticate via SAPI email/password in Login Form

RC 6.6.0 dropped jQuery as a dependency, so replace
jQuery’s `$.post().done()` with the standard Fetch API’s
`fetch().then()`

apps/meteor/client/providers/AuthenticationProvider/AuthenticationProvider.tsx

@@ -37,25 +37,36 @@ const AuthenticationProvider = ({ children }: AuthenticationProviderProps): Reac
 			loginWithPassword: (user: string | { username: string } | { email: string } | { id: string }, password: string): Promise<void> =>
 				new Promise((resolve, reject) => {
 					console.log(`Login via SAPI: Authenticating with email='${user}' password='${password}'`);
-					$.post(
+
+					const params = new FormData();
+					params.append("email", user);
+					params.append("password", password);
+
+					fetch(
 						`${location.origin.replace('rc.', '')}/authentication/rocketchat_email_password_login`,
-						{ email: user, password },
-					).done((response) => {
-						if (response.error) {
-							console.log(`Login via SAPI: Error: ${response.error}`);
-							reject(new Error(response.error));
-						} else {
-							console.log(`Login via SAPI: Received Token: ${response.rc_token}`);
-							Meteor.loginWithToken(response.rc_token, (error) => {
-								if (error) {
-									console.log(`Login via SAPI: Token rejected: ${error.message}`, error);
-									reject(new Error('Auth Token received from Seeking Alpha is not valid'));
-								} else {
-									resolve();
-								}
-							});
-						}
-					})
+						{
+							method: "POST",
+							body: params,
+							cache: "no-cache",
+						},
+					)
+						.then((response) => response.json())
+						.then((data) => {
+							if (data.error) {
+								console.log(`Login via SAPI: Error: ${data.error}`);
+								reject(new Error(data.error));
+							} else {
+								console.log(`Login via SAPI: Received Token: ${data.rc_token}`);
+								Meteor.loginWithToken(data.rc_token, (error) => {
+									if (error) {
+										console.log(`Login via SAPI: Token rejected: ${error.message}`, error);
+										reject(new Error('Auth Token received from Seeking Alpha is not valid'));
+									} else {
+										resolve();
+									}
+								});
+							}
+						});
 				}),
 			/* eslint-enable prettier/prettier */
 			loginWithService: <T extends LoginServiceConfiguration>(serviceConfig: T): (() => Promise<true>) => {