Fix ESM imports on Windows

[nchevsky]

• Fixes ESM imports on Windows fail with ERR_UNSUPPORTED_ESM_URL_SCHEME #3584.

When the requireModule() utility function determines that the given fullpath argument corresponds to an ECMAscript module, it tries to import the module as follows:

import(fullpath)

Node.js' ESM loader requires that the given argument be a file:// URL, but fullpath is instead an absolute path whose form varies by operating system:

	*nix	Windows
fullpath	/foo/bar.js	c:/foo/bar.js
Outcome	✔️ Succeeds because the path can still be interpreted as a URL.	❌ Fails because the path cannot be interpreted as a URL due to the leading drive letter.

The error message on Windows:

┌───────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                                   │
│   There was an error while trying to load the file                                                                │
│   C:\foo\bar.js:                                                                                                  │
│   [ERR_UNSUPPORTED_ESM_URL_SCHEME] Only URLs with a scheme in: file, data are supported by the default ESM        │
│   loader. On Windows, absolute paths must be valid file:// URLs. Received protocol 'c:';                          │
│                                                                                    ^^^^                           │
└───────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

This change solves the problem in a cross-platform fashion by passing fullpath through node:url's pathToFileURL() function, which yields the proper file:// URL that import() expects.

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💡 Missing test disclaimer: requireModule() currently has no tests, and I don't see how one can be written without somehow mocking require() to fail with arbitrary error codes and messages. If you feel requireModule() should absolutely have tests and can provide any suggestions, I'm happy to oblige.

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