Scheme handler: Windows scheme handler does not need admin privileges

[iLLiCiTiT]

Changelog Description

Register scheme handler under CURRENT_USER registry to avoid requirement for admin privileges and to avoid issues connected to multi-user machine.

Additional info

Modification of HKEY_CURRENT_USER\SOFTWARE\Classes does not require admin privileges and adding ayon-launcher there has same effect as in HKEY_CLASSES_ROOT.
User classes have bigger priority over HKEY_CLASSES_ROOT so it should work even if machine already has set up ayon-launcher in HKEY_CLASSES_ROOT.

Testing notes:

1. Open regedit tool (Win + R -> type "regedit" -> Enter) and remove ayon-launcher from HKEY_CLASSES_ROOT (ignore this step if is not there).
2. Build and make installer from this branch.
3. Upload and install the installer on your machine.
4. Start webaction (e.g. application) from AYON server.
5. Application should be starting.

I don't know if we use AYON launcher as windows service anywhere, but I don't know what happens if windows service tries to access HKEY_CURRENT_USER as it is not running "under user".

Resolves #171