fix: esc not working on Windows during fullscreen

[codebytere]

Description of Change

Closes #34301.

Cleans up fullscreen control logic cross-platform.

1. We don't want to call fullscreen_controller()->EnterFullscreenModeForTab in WebContents::EnterFullscreenModeForTab, becuase there's a chance that the user will deny permission via session.setPermissionRequestHandler. Only call this in OnlyEnterFullscreenModeForTab after the user has allowed fullscreening.
2. We also need to ensure that NotifyExclusiveTabAccessLost is called on all platforms in FullscreenController::ExitFullscreenModeInternal() and not just macOS, since Electron's native window impls report state change fairly instantly as well, and so pressing escape won't work on Linux or Windows to un-fullscreen in some circumstances without this change.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed an issue where pressing escape would not un-fullscreen on Windows or Linux in some circumstances.

[VerteDinde]

WOA failure is unrelated

[release-clerk]

Release Notes Persisted

Fixed an issue where pressing escape would not un-fullscreen on Windows or Linux in some circumstances.

[trop]

I was unable to backport this PR to "18-x-y" cleanly;
you will need to perform this backport manually.

[trop]

I was unable to backport this PR to "19-x-y" cleanly;
you will need to perform this backport manually.

[trop]

@codebytere has manually backported this PR to "19-x-y", please check out #34359

[trop]

@codebytere has manually backported this PR to "18-x-y", please check out #34361