Clean up registry lock file after parse failure

[HebaruSan]

I have an old KSP 0.90 install that has a corrupted registry.json file (truncated in the middle of a string in the section about the installed files). If I try to access this instance with RegistryManager.Instance(), an appropriate JsonReaderException is thrown in the constructor of RegistryManager and no access is possible, but the registry.locked file is still in the folder (it is created by GetLock immediately before the parsing is attempted). Depending on exactly what the process does after that, additional exceptions can occur at random when various of the object's partially constructed resources are destroyed by the garbage collector. The lock file does disappear later when the process exits.

When a constructor throws an exception, this means the requested object cannot be created, so it should first clean up any resources it has allocated up to that point, including things like lock files, so the program is in a consistent state.

This change intercepts parsing exceptions in the constructor and calls Dispose to clean up, just like the destructor does, before re-throwing the exception. This causes the lock file to be cleaned up if the registry can't be parsed, while still alerting the calling code to the problem. It also fixes the seemingly random exceptions that I was seeing afterwards.