New Logo, Migrate to .NET Core 3.1, Separate Bootstrapper from Form!

I've reassembled the entire project into .NET Core, which will give the mod manager full access to the latest features available in C#
As an awkward side effect, the exe now requires a DLL file next to it to operate correctly.

The primary focus of this update was to get the bootstrapper separated from the form that displays what it's doing. The StudioBootstrapper is now an independent class with events that provide a feed of what it's doing, which the bootstrapper form subscribes to. I'm doing this so I can use the mod manager as a dependency in my client tracker directly, instead of having to fork the bootstrapper code into there.

I've given the UI a light facelift and updated the logo of the application to reflect Roblox Studio's new upcoming logo.
Enjoy! Let me know if you encounter any problems.

Combating malware misdiagnosis.

I haven't posted some recent commits here as releases so I'm doing that now.
This latest release clears up some recent malware misdiagnoses being applied to this program.

The application is now signed with a private key from me, and uses a debug assembly so that everything its doing is clear to any antivirus programs analyzing it. I've also fixed several bugs with the installer since the last release.

Working around ClientSettings endpoint outage.

Roblox's ClientSettings API went down this morning, but the ClientSettingsCdn endpoint still seems to be working. I will be patching in a proper fail-safe for this later today or tomorrow, but I wanted to address this bug immediately since it completely bricked the launcher.

Add support for ExtraContent folder.

Roblox made a change to the deployment spec which requires a patch to the mod manager to work correctly.
Any cases where files are extracted to an ExtraContent root directory are instead redirected to the existing content directory.

Fixed crash related to SSL/TLS secure channel.

Fixed a very minor, but critical bug that was making the app crash on startup.
The ServicePointManager now uses TLS 1.2 to handle HTTPS no matter what.

Migrate from gametest to sitetest

Roblox has decided to merge their engine/website deployments together, thus dropping the usage of gametest{X}.robloxlabs in favor of sitetest{X}.robloxlabs. I have updated the branch dropdown list to use their sitetest branches instead, as the gametest branches are now effectively frozen in time.

Added version targeting support!

You can now choose to either use the latest version of the branch you've selected, or choose a specific previous version of Roblox Studio!

Only builds from 9/9/2019 and later are supported. Versions earlier than that do not comply with how I'm presently bootstrapping Roblox Studio.

I also cleaned up some old unused code, and made some other minor tweaks.
Merry Christmas Eve!