t/135 Removed "vanilla" Lark

[dkonopka]

Suggested merge commit message (convention)

Other: Removed styles for ck-editor-toolbar. Closes ckeditor/ckeditor5#3395.
Other: Removed border from ck-button class.
Tests: Wrapped buttons and icons in ToolbarView in manual theme test.

[oleq]

Some impressions and bugs:

• I'd get rid of these three variables too

  ckeditor5-theme-lark/theme/ckeditor5-ui/globals/_colors.css

  Lines 98 to 100 in 633bdc1

  	--ck-color-editor-border: var(--ck-color-base-border);
  	--ck-color-editor-toolbar-background: var(--ck-color-base-foreground);
  	--ck-color-editor-dropdown-background: var(--ck-color-base-background);

  . The point of this refac is to remove the middle (vanilla) layer completely. Default styles (colors) should consider the editor too.
• I'd wrap all the buttons in the lark MT in .ck-toolbar. We can do that by code, creating a ToolbarViews to speed it up. ATM it's hard to tell what's going on
  

[oleq]

The balloon should not have the same background as the toolbar

[dkonopka]

Ok, variables removed, manual test updated, I've added ToolbarView for every button/icon group.

@oleq Let's talk about balloon background, why (and when? :D) we decided to use two different backgrounds for toolbar and balloon? Currently, it looks really weird, maybe we should consider one for every panel in the editor?

toolbar bg - hsl(0, 0%, 98%)

balloon bg - hsl(0, 0%, 100%)

[oleq]

We never considered a balloon with a darker background when working on ckeditor/ckeditor5#645. IMO white balloons provide a better contrast between the wall of edited text and the UI and that's a good enough reason. It's more evident when in the context

[oleq]

Anyway, we can discuss the topic in a separate issue. Let's focus on the task at hand and not touch the design we came up with.

[dkonopka]

Agree. I'll make follow-up then and bring back white background for the balloon.

edit: you were faster :D