Add ability to lock object placement blueprint to hit area in osu!taiko editor

[Hiviexd]

I thought about this idea and I strongly think it'd improve familiarity for mappers coming from stable, it mimics stable's UX of focusing on the timeline when placing objects and not having to pay attention to placement on the playfield.

I tried sketching this in a local branch, tried mapping with it a bit and I found it significantly more natural. Can PR it if this gets dev approval.

one may wonder why not just have your cursor stationary on the hit area? from my experience mapping multiple times on lazer, I found this to be one extra thing to focus on having correct which gets annoying in prolonged sessions. the way this mimics stable's UX makes it all that natural IMO.

This would be a default-off setting with it being under the "show speed changes" one.

[ziv-vy]

Not sure if this comparison helps (since they are completely different rulesets), but something similar to this was attempted in the sentakki editor. While it initially felt good, it was actually slowing down my mapping by a very significant amount. Instead of just moving my mouse/pen to the proper beat, I had to use the scroll wheel or arrow keys to manually move a few beats behind.

Once I (permanently) disabled this feature, my mapping accelerated by a very significant amount.

Personally, I think that this wouldn't really be a great feature. It'd be better if taiko mappers got used to the much faster workflow of using snap grids instead of adding a compatibility feature which limits the speed of their mapping just to avoid change.

[peppy]

I'm okay with this being added as an option.