module: reduce circular dependency of internal/modules/cjs/loader

Previously `internal/bootstrap/pre_execution.js` requires
`internal/modules/cjs/loader.js` which in turn requires
`internal/bootstrap/pre_execution.js`. This patch moves the
entry point execution logic out of `pre_execution.js` and
puts it into `internal/modules/run_main.js`. It also tests
that `Module.runMain` can be monkey-patched before further
deprecation/refactoring can be done.

Also added an internal assertion `hasLoadedAnyUserCJSModule`
for documentation purposes.

PR-URL: https://github.com/nodejs/node/pull/30349


Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>