Adds the ability to connect/login to an account via the settings and
auto-configuration dialogs.  Checks registered Auth objects, and if the
Auth object matches the currently selected service in the settings
window or auto-configuration dialog, will display "connect account"
buttons for the user to be able to click (which are optional, they can
still use stream keys if they'd prefer).

You could also say..  obs-fuscation.

Allows the ability to authenticate to a specific service.  Typically via
OAuth.

Adds a function for initializing browser and cookies in a separate
thread while, and while waiting for it to complete, show a dialog
stating that the browser is currently being loaded.  Allows the ability
to safely prevent the user from taking any action without actually
freezing up the UI thread.

Allows the ability to switch cookies between profiles.  Allows the
ability to, for example, switch streaming service accounts between
profiles for proper access to the pages displayed by the browser panels
(such as chat windows).

Makes it so that services can have custom handling on a per-service
basis.  The bottom part of the service pane is now a stacked widget
which can now be customized for different types of services
(particularly OAuth services).

Allows using it outside of the constructor.

Adds OBSBasic::Get() to just quickly return the main window.

Adds functions for executing functions within separate threads without
blocking the user interface, or by blocking the user interface with a
dialog box.

Allows creating a QThread via an std::function.  A backward-compatible
alternative to QThread::create for Qt versions older than 5.10 (when it
became available in Qt).

Allows specifying extra headers.

Allows specifying a timeout for the operation.

Currently, browser panel is only supported on windows.  So rather than
have to check for _WIN32 in the code everywhere, just move the WIN32
check to cmake, that way we don't have to have _WIN32 checks in the code
everywhere the browser panel code is used, and do not have to remove a
whole bunch of unnecessary _WIN32 #ifdefs for other operating systems
when browser panel support is added for them.

The "Custom" service has been moved, and is now an item called "Custom"
in the "Services" combo box.  This simplifies the stream page of
auto-configuration and removes an unnecessary widget.  Overall a minor
but nice slimline/improvement on user experience.

Add GPL Cooperation Commitment to base directory

obs-filters: Fix unused parameter warnings

Closes obsproject/obs-studio#1602

The GPL is not an EULA and thus it doesn't need to be agreed to.

See also:
https://github.com/HandBrake/HandBrake/pull/1776
https://github.com/videolan/vlc/commit/c07d72146286da935a04be579d6b60bf633cbceb

Closes obsproject/obs-studio#1597

win-capture: Start user-facing monitor count at 1

libobs: Fix scanf type specifiers

frontend-tools: Call modified prop callbacks on script load/reload

This change means that the modified callback for a scripts properties is
always called when first loaded or on a reload. This behavior matches
the properties view for sources, where all modified callbacks are called
when the window opens. This change therefore treats reloading as
equivalent to reopening.

CI: Use modified macOS QT installer

Operating systems don't report monitors from 0, so OBS shouldn't
either. This avoids user confusion when display capture doesn't work.
This does not change monitor count internally.

UI: add a default black background to the PGM output of the multiview

UI: Add support for Restream "Auto" server in auto-config

decklink: Remove redundant const qualifiers

rtmp-services: Remove LiveEdu from services

They now provide ingest URLs on demand in their panel.
The ones in our list point to random OVH IPs that are likely assigned to
new customers by now and refuse the connection on TCP port 1935.

rtmp-services: Update Twitch and Smashcast ingests