fix(nest): prevent concurrent NestJS application initialization

[lnqs]

Added a locking mechanism to ensure only one NestJS application is initialized at a time, avoiding potential race conditions during simultaneous requests.

[lnqs]

I'm working on a NestJS app using vite-plugin-node with a React frontend that triggers multiple requests at the same time. This reliably lead to all kind weird errors right after the dev server was started, when the web frontend was still open in the browser. After some investigation, I realized the NestJS app was initialized multiple times.

This fix locks (deadly stupid, with a busy lock) the NestJS initializing to prevent this issue. Seems to work on my project.
A cleaner approach would probably be to have some kind of async lock in place, but I don't think it's worth adding a new dependency or more complex code. The performance impact of the loop and timeout shouldn't be relevant, given this happens only on app start or reload and when multiple requests are performed at the same time.