Kobo: Refactor various aspects of the Kaleido/MTK support (#12221)

* UIManager: Let the fb backend deal with Kaleido wfm promotion. This fixes a number of quirks that poisoned the refresh queue with spurious full-screen refreshes. See https://github.com/koreader/koreader-base/pull/1865 for more details.
* This also means we now disable Kaleido waveform modes when color rendering is disabled (remember to trash your thumbnail cache if you don't want to mix color w/ grayscale thumbnails, though).
* UIManager: Merge refreshes that share an edge, because that was driving me nuts (and would have most likely been merged by the kernel anyway). A perfect test-case is the FM, which trips two separate refreshes because of its title bar.
* ReaderFlipping: Use sensible dimensions, so that we only refresh the icon's region.
* ReaderBookmark: Only refresh the dogear instead of the whole page when toggling bookmarks.
* NetworkSetting: Make it a real boy, so it consistently refreshes properly on dismiss instead of relying on UIManager saving the day.
* Kobo: Aggressively prevent *both* suspend & standby while MTK devices are plugged-in, as both will horribly implode the kernel (we previously only prevent standby while charging).
* Kobo: Switch to 8bpp on B&W MTK devices (or when color rendering is disabled on Kaleido panels).

frontend/ui/widget/container/leftcontainer.lua

@@ -19,7 +19,9 @@ function LeftContainer:paintTo(bb, x, y)
     if BD.mirroredUILayout() and self.allow_mirroring then
         x = x + (self.dimen.w - contentSize.w) -- as in RightContainer
     end
-    self[1]:paintTo(bb, x , y + math.floor((self.dimen.h - contentSize.h)/2))
+    self.dimen.x = x
+    self.dimen.y = y + math.floor((self.dimen.h - contentSize.h)/2)
+    self[1]:paintTo(bb, self.dimen.x, self.dimen.y)
 end
 
 return LeftContainer