compartment-mapper: dynamic require of "node:"-prefixed builtins fails

[boneskull]

Describe the bug

While I was careful to add a test case for "dynamic require of a builtin module", that test case only covers a bare module specifier (cluster).

Changing cluster to node:cluster fails the test:

  Rejected promise returned by test. Reason:

  TypeError {
    message: 'Failed to load module "node:cluster" in package "file:///path/to/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/" (1 underlying failures: The URL must be of scheme file',
  }

  TypeError: Failed to load module "node:cluster" in package "file:///path/to/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/" (1 underlying failures: The URL must be of scheme file
      at throwAggregateError (file:///path/to/ses/src/module-load.js:557:11)
      at loadNow (file:///path/to/ses/src/module-load.js:654:3)
      at Compartment.importNow (file:///path/to/ses/src/compartment.js:187:5)
      at require (file:///path/to/compartment-mapper/src/parse-cjs-shared-export-wrapper.js:149:33)
      at Proxy.eval (eval at <anonymous> (eval at makeEvaluate (file:///path/to/ses/src/make-evaluate.js:92:27)), <anonymous>:5:1)
      at Object.execute (file:///path/to/compartment-mapper/src/parse-cjs.js:56:13)
      at execute (file:///path/to/ses/src/module-instance.js:101:24)
      at compartmentImportNow (file:///path/to/ses/src/compartment.js:103:3)
      at file:///path/to/ses/src/compartment.js:160:27
      at async file:///path/to/compartment-mapper/test/dynamic-require.test.js:303:25

This is reproducible outside of the @endo/compartment-mapper's test environment (I found it via @lavamoat/node's testing environment; lol).

Steps to reproduce

1. Modify compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/index.js:

   diff --git a/packages/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/index.js b/packages/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/index.js
   index f64a83d77acdc2d1b5b5b9ffe254108d2c0fa567..972b76820199e55ef0c0624417708c4a432a9cb4 100644
   --- a/packages/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/index.js
   +++ b/packages/compartment-mapper/test/fixtures-dynamic/node_modules/hooked-app/index.js
   @@ -1,5 +1,5 @@
   exports.isOk = require('hooked').isOk;
   
   -const builtin = 'cluster';
   +const builtin = 'node:cluster';
   
   require(builtin);
   \ No newline at end of file

2. Execute test (from packages/compartment-mapper):

   npx ava test/dynamic-require.test.js -c 1 -m 'inter-package and exit module dynamic require works'

3. Observe failure akin to the trace pasted above.

Expected behavior

It should be the same behavior as exhibited sans-prefix.

Additional context

This is likely my fault, so I will fix it.

[boneskull]

Also: I would love a proper stack trace, but I'm not sure how to get any better; we're already using errorTaming: 'unsafe'