delete bloated registry items

[xiaonian233]

delete bloated registry items.
check and delete the registry when launching easytier-gui.
just making modifications to easytier-gui instead of easytier-core

[KKRainbow]

Would you consider integrating this into the easytier-core? The core module also encounters the same issue.

[xiaonian233]

the check & delete code will run before "create_tun".
but I think there must be a better location for this part of code. I tried the "close" and "drop" functions from ring.rs, but the results were always unsatisfactory. I will continue to find the best position. At the same time, due to my skill issues, the code may need to be optimized to better integrate in to the entire program.