Preserve initial bank angle of selected segment

Current behaviour when selecting a segment with bank:
<img width="795" alt="image" src="https://github.com/Open-Source-Transport/roblox-path-plugin/assets/129159900/ddf546d5-6b8b-490b-8b88-c5fff38c260a">

This makes connecting banked curves difficult.

I propose the initial bank is preserved and the plugin gradually adjusts to its settings, but other suggestions are welcome.