chore: Centralize env parsing, validation, defaults, and deprecation notices (#3487)

* chore: Centralize env parsing, defaults, deprecation

* wip

* test

* test

* tsc

* docs, more validation

* fix: Allow empty REDIS_URL (defaults to localhost)

* test

* fix: SLACK_MESSAGE_ACTIONS not bool

* fix: Add SMTP port validation

server/services/web.ts

@@ -13,8 +13,9 @@ import routes from "../routes";
 import api from "../routes/api";
 import auth from "../routes/auth";
 
-const isProduction = env.NODE_ENV === "production";
-const isTest = env.NODE_ENV === "test";
+const isProduction = env.ENVIRONMENT === "production";
+const isTest = env.ENVIRONMENT === "test";
+
 // Construct scripts CSP based on services in use by this installation
 const defaultSrc = ["'self'"];
 const scriptSrc = [
@@ -36,7 +37,7 @@ if (env.CDN_URL) {
 export default function init(app: Koa = new Koa()): Koa {
   if (isProduction) {
     // Force redirect to HTTPS protocol unless explicitly disabled
-    if (process.env.FORCE_HTTPS !== "false") {
+    if (env.FORCE_HTTPS) {
       app.use(
         enforceHttps({
           // @ts-expect-error ts-migrate(2345) FIXME: Argument of type '{ trustProtoHeader: boolean; }' ... Remove this comment to see the full error message