module: unflag --experimental-require-module

[joyeecheung]

This unflags --experimental-require-module so require(esm) can be used without the flag. For now, when require() actually encounters an ESM for the first time in a process, it will still emit an experimental warning. To opt out of the feature, --no-experimental-require-module can be used.

There are some tests specifically testing ERR_REQUIRE_ESM. Some of them are repurposed to test --no-experimental-require-module. Some of them are modified to just expect loading require(esm) to work, when it's appropriate.

This is expected to go out in 23 and get some testing before being backported to older LTS.

See #55085 (comment) for a summary of the impact of this on loading the high-impact npm packages.

For more background on the motivation of require(esm) see #51977 - TL;DR: it helps accelerating ESM adoption in the ecosystem as package authors can start shipping native ESM with less breakage to their CJS users; it also helps frameworks and tools that take plugins to support native ESM in user/plugin code whilst they are still navigating their own migration to ESM.

Note to releasers: in the release announcements we should emphasize the implications this has on top-level await is limited to require(). In entry points or modules that are only ever imported, top-level await works fine as before. Only when one tries to use the synchronous require() to evaluate a module that awaits at module loading time (top-level), it obviously would not work, not that it ever worked before require() supports ESM, just that it's now the only significant remaining exception for require(esm).

Refs: #52697