add quick open/input color registers

[chaseadamsio]

The goal of this PR is to extract the color registration for the quick opener/quick input so that it can be styled separately from the Sidebar.

Currently, it's pulling whatever styles are create on the sidebar for foreground and background. This isn't intuitive for theme developers (personally, I struggled to remember which register to use and I only figured it out because of others having the same experience and discussing on Stack Overflow). It's also limiting in that it forces theme developers into making a decision about both the sidebar and the quick picker.

I want to propose registering two new color selectors:

• "quickOpen.background"
• "quickOpen.foreground"

Here's an example after running ./scripts/code.sh on master and the PR branch.

Before (master):

After (freeQuickPickerColors, in my theme I set the background color to a darker black fo the "quickOpen.background" and left "sideBar.background" the same):

[aeschli]

The changes make sense to me, but assigning to @chrmarti as he's the owner of the (various) quick pick UIs

[chaseadamsio]

Hey @alexr00, any chance you've been able to mull this over? If you have any questions / suggestions I'm open to them!

[chrmarti]

Thanks @chaseadamsio !

[craigcosmo]

it's not working. "quickOpen.background":"#fff" doesn't make my picker white.

[chaseadamsio]

Looks like there was a commit here: cc6b5c3 where quickOpen was replaced with quickInput and was mentioned in this comment. but not updated here.

For reference, for anyone who finds this in the future, the following:

"quickOpen.background"
"quickOpen.foreground"

has been replaced with:

"quickInput.background"
"quickInput.foreground"