…ealm scopes

In order to automatically run tests not only in a ShadowRealm created in a
window scope, but also in ShadowRealms created in other realms, change the
'shadowrealm' global type to a collection, and rename the existing
ShadowRealm handler to 'shadowrealm-in-window'.

As per whatwg/html#9893, ShadowRealmGlobalScope
should have a `self` attribute already. There is no need to monkeypatch it
for the test harness.

We will add multiple ShadowRealm handlers, and they will all need to set
up certain global properties. Avoid repeating this code in each handler
as well as in idlharness-shadowrealm.js.

This should also increase readability, which is good since the ShadowRealm
setup code can be confusing.

This will add to any test with global=shadowrealm in its metadata, an
.any.shadowrealm-in-shadowrealm.html variant.

The test wrapper creates an outer ShadowRealm, which creates an inner
ShadowRealm and runs the tests inside that, relaying the results through
the outer ShadowRealm.

This will add to any test with global=shadowrealm in its metadata, an
.any.shadowrealm-in-dedicatedworker.html variant.

The test loads an intermediate .any.worker-shadowrealm.js wrapper into a
Worker, and forwards the message port to the Worker's message port so that
fetch_tests_from_worker can receive the results.

This will add to any test with global=shadowrealm in its metadata, an
.any.shadowrealm-in-sharedworker.html variant.

The test loads the same intermediate .any.worker-shadowrealm.js wrapper as
.any.shadowrealm-in-dedicatedworker.html, but populates a 'port' variable
with the port received from the connect event, instead of calling the
global postMessage since that won't work in a SharedWorker.

This will add to any test with global=shadowrealm in its metadata, an
.any.shadowrealm-in-serviceworker.html variant.

We have to use a slightly different .any.serviceworker-shadowrealm.js
wrapper from the wrapper used for the other types of workers, because
dynamic import() is forbidden in ServiceWorker scopes. Instead, add a
utility function to set up a fakeDynamicImport() function inside the
ShadowRealm which uses the fetch adaptor to get the module's source text
and evaluate it in the shadowRealm.

Also add a case for ServiceWorkers to getPostMessageFunc(), which returns
a postMessage() drop-in replacement that broadcasts the message to all
clients, since test result messages from the ShadowRealm are not in
response to any particular message received by the ServiceWorker.

Note '.https.' needs to be added to the test path.

This will add to any test with global=shadowrealm in its metadata, an
.any.shadowrealm-in-audioworklet.html variant.

The wrapper here is similar to the one for ServiceWorkers, since dynamic
import() is also forbidden in worklet scopes. But additionally fetch() is
not exposed, so we add a utility function to set up the ability to call
the window realm's fetch() through the AudioWorklet's message port.

We also add /resources/testharness-shadowrealm-audioworkletprocessor.js to
contain most of the AudioWorklet setup boilerplate, so that it isn't
written inline in serve.py.

Note '.https.' needs to be added to the test path.