feat: add additional remote APIs filtering

[miniak]

Description of Change

Follow up to #15014:

• remote.getBuiltin() by handling remote-get-builtin
• remote.getCurrentWindow() by handling remote-get-current-window
• remote.getCurrentWebContents() by handling remote-get-current-web-contents
• <webview>.getWebContents() (implemented via remote.getGuestWebContents()) by handling remote-get-guest-web-contents

I can be used to return a proxied or filtered version of the electron APIs.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Allowed filtering of remote.getBuiltin(), remote.getCurrentWindow(), remote.getCurrentWebContents and <webview>.getWebContents().

[ppontes]

LGTM

[miniak]

@MarshallOfSound, @nornagon can you please review?

[nornagon]

test failures look relevant

[miniak]

@nornagon some tests were broken after nodeIntegration was disabled by default. fixed those

[release-clerk]

Release Notes Persisted

Allow filtering of remote.getBuiltin(), remote.getCurrentWindow(), remote.getCurrentWebContents and <webview>.getWebContents().

[miniak]

/trop run backport-to 4-0-x

[trop]

The backport process for this PR has been manually initiated,
sending your 1's and 0's to "4-0-x" here we go! :D

[trop]

I was unable to backport this PR to "4-0-x" cleanly;
you will need to perform this backport manually.