Share env vars client-side using @Public decorator (#6627)

* fix: public env vars using decorator

* fix: relocate

* fix: use env.public

* fix: register public env vars across plugins

* fix: test

* fix: tsc

* fix: mark remaining ones as public

* fix: move oidc ones to plugin

* fix: prevent overwrite

* fix: review

server/utils/decorators/Public.ts

@@ -0,0 +1,37 @@
+import "reflect-metadata";
+import isUndefined from "lodash/isUndefined";
+import type { Environment } from "@server/env";
+
+const key = Symbol("env:public");
+
+/**
+ * This decorator on an environment variable makes that variable available client-side
+ */
+export function Public(target: any, propertyKey: string) {
+  const publicVars: string[] = Reflect.getMetadata(key, target);
+
+  if (!publicVars) {
+    return Reflect.defineMetadata(key, [propertyKey], target);
+  }
+
+  publicVars.push(propertyKey);
+}
+
+export class PublicEnvironmentRegister {
+  private static publicEnv: Record<string, any> = {};
+
+  static registerEnv(env: Environment) {
+    process.nextTick(() => {
+      const vars: string[] = Reflect.getMetadata(key, env);
+      (vars ?? []).forEach((key: string) => {
+        if (isUndefined(this.publicEnv[key])) {
+          this.publicEnv[key] = env[key];
+        }
+      });
+    });
+  }
+
+  static getEnv() {
+    return this.publicEnv;
+  }
+}