Add back the 1D OKLab color picker

[HybridDog]

There are complaints that with the 2D colour picker only fully-saturated colours can be selected and requests to add back a saturation slider.

This reverts commit d7e6703, i.e. it adds back the 1D sliders next to the 2D picker.

[HybridDog]

Related discussions:

• Discussion about the 1D OKLab colour picker's usefulness: OKLab color picker: Why? #2323 (@Semphriss)
• Replacement of the 1D OKLab colour pickers by a 2D one: [NOSQUASH] Editor: Replace the OKLab color picker by a 2D color picker #2895
• Request to add a saturation slider: Add a saturation slider underneath the color picker #3128 (@Eauix)
• Probably abandoned Pull Request to add a saturation slider: Added color saturation slider #3251 (@nathaniel-jb, @Frostwithasideofsalt)

[MatusGuy]

Knowing that this is a revertion of an existing commit, it LGTM (code, test).

However, and I know this is not quite what is being referenced here, soon I think there should be a way to use an actual RGB 2D color picker. I think an OKLab color picker makes more sense as 1d sliders than as a 2d square. This is because with a 2d oklab color picker, some colors are easier to pick than others, as opposed to a normal RGB version.

[Eauix]

I hadn't had the time to test it properly yet, but I noticed that the saturation slider gets altered automatically in some unpredictable ways when you change the color's brightness, which is kinda annoying

The thing is, I don't remember if this situation happened before the 2d color picker was implemented, I'll try to test an old version to tell this

Also, it'd be nice if the 2d picker could change its saturation to represent the true color it'll select when you move the saturation slider

But tbh, I wouldn't mind if the 2d picker was just removed

[MatusGuy]

I hadn't had the time to test it properly yet, but I noticed that the saturation slider gets altered automatically in some unpredictable ways when you change the color's brightness, which is kinda annoying

I believe this is a byproduct of OKLab.