feat: preloads and nodeIntegration in iframes (#16425)

* feat: add support for node / preloads in subframes

This feature has delibrately been built / implemented in such a way
that it has minimum impact on existing apps / code-paths.
Without enabling the new "nodeSupportInSubFrames" option basically none of this
new code will be hit.

The things that I believe need extra scrutiny are:

* Introduction of `event.reply` for IPC events and usage of `event.reply` instead of `event.sender.send()`
* Usage of `node::FreeEnvironment(env)` when the new option is enabled in order to avoid memory leaks.  I have tested this quite a bit and haven't managed to cause a crash but it is still feature flagged behind the "nodeSupportInSubFrames" flag to avoid potential impact.

Closes #10569
Closes #10401
Closes #11868
Closes #12505
Closes #14035

* feat: add support preloads in subframes for sandboxed renderers

* spec: add tests for new nodeSupportInSubFrames option

* spec: fix specs for .reply and ._replyInternal for internal messages

* chore: revert change to use flag instead of environment set size

* chore: clean up subframe impl

* chore: apply suggestions from code review

Co-Authored-By: MarshallOfSound <samuel.r.attard@gmail.com>

* chore: clean up reply usage

* chore: fix TS docs generation

* chore: cleanup after rebase

* chore: rename wrap to add in event fns

lib/renderer/window-setup.js

@@ -26,7 +26,7 @@
 const { defineProperty, defineProperties } = Object
 
 // Helper function to resolve relative url.
-const a = window.top.document.createElement('a')
+const a = window.document.createElement('a')
 const resolveURL = function (url) {
   a.href = url
   return a.href