esm: remove globalPreload hook (superseded by initialize)

[JakobJingleheimer]

This PR removes the globalPreload module customization hook. It is no longer needed now that its functionality is provided by the register API paired with the initialize hook. You can see examples of refactoring from globalPreload to register / initialize in #49465 and in some of the updated tests in this PR.

Besides removing the hook itself, the test-esm-loader-hooks.mjs test describe('globalPreload' block and test-esm-loader-side-effect.mjs were removed. These were testing parts of globalPreload, like that its communications ports work, that we already have separate tests for covering the superseding equivalent in register / initialize; or they were testing things that we don’t need tests for outside of the globalPreload context, such that global variables declared in a preload script are accessible on the main thread. (The new API calls register from the main thread, and global variables can be declared there, and we don’t need a test that global variables declared on the main thread can be read on the main thread.)

This PR completes the loaders roadmap Milestone 2.

Notable changes

Module customization hook globalPreload removed; use register and initialize instead

The module customization hook globalPreload has been removed. Instead, use register to send data from the application thread to the customization hooks, and the initialize hook to establish a communications channel between the threads.