fix(ext/node): clear tz cache when setting process.env.TZ

[littledivy]

Fixes #18623

Intercepts the assignment to TZ env var and updates tz cache. Matches Node's behaviour (ref)

import process from "node:process"

console.log(new Date().toString());
process.env.TZ = 'Asia/Tokyo';
console.log(new Date().toString());

Sun Jan 26 2025 10:00:47 GMT+0530 (India Standard Time)
Sun Jan 26 2025 13:30:47 GMT+0900 (Japan Standard Time)

[bartlomieju]

Can you add a test that uses Deno.env API too?

[petamoriken]

IMHO, instead of using Deno.env.TZ according to process.env.TZ, it would be better to have a accessor property API e.g. Deno.timeZone.

My bad. Apparently it is already supported.
#11053 (comment)