MongoDB Transactions (#12335)

* add run-rs to dependencies

* wip: add replica set to api unit github action

* wip: add replica set to api unit github action

* wip: fix gh actions mongodb replica set setting

* usa replica set for integration tests

* add correct mongodb version matrix for integration tests

* use different db connection on gh actions

* Revert "use different db connection on gh actions"

This reverts commit aa8db759d3.

* add example transaction

* add mongo script to package.json

* abstract mongodb utils, connect using hostname on windows

* npm scripts: mongo -> mongo:dev

* add setup script for run-rs on windows

* gh actions: run in test environment

* remove test files

* better error handling, use cross-spawn to avoid issues on windows

* fix lint

website/server/libs/mongodb.js

@@ -0,0 +1,37 @@
+import os from 'os';
+import nconf from 'nconf';
+
+const IS_PROD = nconf.get('IS_PROD');
+
+// Due to some limitation in the `run-rs` module that is used in development
+// In order to connect to the database on Windows the hostname must be used
+// instead of `localhost`.
+// See https://github.com/vkarpov15/run-rs#notes-on-connecting
+// for more info.
+//
+// This function takes in a connection string and in case it's being run on Windows
+// it replaces `localhost` with the hostname.
+export function getDevelopmentConnectionUrl (originalConnectionUrl) {
+  const isWindows = os.platform() === 'win32';
+
+  if (isWindows) {
+    const hostname = os.hostname();
+    return originalConnectionUrl.replace('mongodb://localhost', `mongodb://${hostname}`);
+  }
+
+  return originalConnectionUrl;
+}
+
+export function getDefaultConnectionOptions () {
+  const commonOptions = {
+    useNewUrlParser: true,
+    useUnifiedTopology: true,
+  };
+
+  return !IS_PROD ? commonOptions : {
+    // See https://mongoosejs.com/docs/connections.html#keepAlive
+    keepAlive: true,
+    keepAliveInitialDelay: 300000,
+    ...commonOptions,
+  };
+}