refactor: Use ES modules for internal runtime code (#17648)

This PR refactors all internal js files (except core) to be written as
ES modules.
`__bootstrap`has been mostly replaced with static imports in form in
`internal:[path to file from repo root]`.
To specify if files are ESM, an `esm` method has been added to
`Extension`, similar to the `js` method.
A new ModuleLoader called `InternalModuleLoader` has been added to
enable the loading of internal specifiers, which is used in all
situations except when a snapshot is only loaded, and not a new one is
created from it.

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

cli/tests/integration/run_tests.rs

@@ -3844,3 +3844,15 @@ itest!(node_prefix_missing {
   envs: env_vars_for_npm_tests_no_sync_download(),
   exit_code: 1,
 });
+
+itest!(internal_import {
+  args: "run run/internal_import.ts",
+  output: "run/internal_import.ts.out",
+  exit_code: 1,
+});
+
+itest!(internal_dynamic_import {
+  args: "run run/internal_dynamic_import.ts",
+  output: "run/internal_dynamic_import.ts.out",
+  exit_code: 1,
+});