chore: Move remaining auth methods to plugins (#4900)

* Move Google, Email, and Azure to plugins

* Move OIDC provider, remove old loading code

* Move AuthLogo to plugin

* AuthLogo -> PluginIcon

* Lazy load plugin settings

server/models/helpers/AuthenticationHelper.ts

@@ -1,9 +1,70 @@
-import { find } from "lodash";
+/* eslint-disable @typescript-eslint/no-var-requires */
+import path from "path";
+import { glob } from "glob";
+import Router from "koa-router";
+import { find, sortBy } from "lodash";
 import env from "@server/env";
 import Team from "@server/models/Team";
-import providerConfigs from "../../routes/auth/providers";
+
+export type AuthenticationProviderConfig = {
+  id: string;
+  name: string;
+  enabled: boolean;
+  router: Router;
+};
 
 export default class AuthenticationHelper {
+  private static providersCache: AuthenticationProviderConfig[];
+
+  /**
+   * Returns the enabled authentication provider configurations for the current
+   * installation.
+   *
+   * @returns A list of authentication providers
+   */
+  public static get providers() {
+    if (this.providersCache) {
+      return this.providersCache;
+    }
+
+    const authenticationProviderConfigs: AuthenticationProviderConfig[] = [];
+    const rootDir = env.ENVIRONMENT === "test" ? "" : "build";
+
+    glob
+      .sync(path.join(rootDir, "plugins/*/server/auth/!(*.test).[jt]s"))
+      .forEach((filePath: string) => {
+        const { default: authProvider, name } = require(path.join(
+          process.cwd(),
+          filePath
+        ));
+        const id = filePath.replace("build/", "").split("/")[1];
+        const config = require(path.join(
+          process.cwd(),
+          rootDir,
+          "plugins",
+          id,
+          "plugin.json"
+        ));
+
+        // Test the all required env vars are set for the auth provider
+        const enabled = (config.requiredEnvVars ?? []).every(
+          (name: string) => !!env[name]
+        );
+
+        if (enabled) {
+          authenticationProviderConfigs.push({
+            id,
+            name: name ?? config.name,
+            enabled,
+            router: authProvider,
+          });
+        }
+      });
+
+    this.providersCache = sortBy(authenticationProviderConfigs, "id");
+    return this.providersCache;
+  }
+
   /**
    * Returns the enabled authentication provider configurations for a team,
    * if given otherwise all enabled providers are returned.
@@ -11,17 +72,12 @@ export default class AuthenticationHelper {
    * @param team The team to get enabled providers for
    * @returns A list of authentication providers
    */
-  static providersForTeam(team?: Team) {
+  public static providersForTeam(team?: Team) {
     const isCloudHosted = env.isCloudHosted();
 
-    return providerConfigs
+    return AuthenticationHelper.providers
       .sort((config) => (config.id === "email" ? 1 : -1))
       .filter((config) => {
-        // Don't return authentication methods that are not enabled.
-        if (!config.enabled) {
-          return false;
-        }
-
         // Guest sign-in is an exception as it does not have an authentication
         // provider using passport, instead it exists as a boolean option.
         if (config.id === "email") {