Rename SessionDebugUI.ts file to DebugUI.ts

[kalwalt]

I think that it should better rename the SessionDebugUi.ts to DebugUI.ts as the old one was arjs-debugui.js, SessionDebugUI seems to contain only the SessionDebugUI class instead there is also AnchorDebugUI class, the actual name of the file is confusing.

[kalwalt]

done with commit abdf23d and 56d8bb8