Add a way to disable Tor via admin policy

Test plan

1. Fresh install of Brave (clean profile)
2. Open regedit
3. For 64 bit, create the following keys: BraveSoftware\Brave under the existing key: HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Policies\ (for 32 bit, you can edit HKEY_LOCAL_MACHINE\SOFTWARE\Policies\)
4. Create a DWORD value at this path called TorDisabled and set the value as 1
5. Launch Brave
6. Verify Managed by your organization shows as the last item under the hamburger menu
7. If you click Managed by your organization, it should take you to brave://management
8. Verify no Tor options are shown in the UI
9. Exit Brave
10. Open the profile directory (%USERPROFILE%\AppData\Local\BraveSoftware\Brave-Browser\User Data)and look for the Tor executable (usually under a path like cpoalefficncklhjfpglfiplenlpccdb\1.0.6). It should NOT be there.

Original issue description

https://twitter.com/dlepi/status/1012732537196765189

Via a method like these work: https://www.chromium.org/administrators/policy-list-3

[bsclifton]

@notoriousturtle starting Monday, @simonhong will be looking at a group policy to completely disable Tor. Please stay tuned

[billrob]

I had to have my team uninstall this browser from our company’s computers because of TOR.