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/apps/reader/modules/readerrolling.lua

@@ -1863,7 +1863,7 @@ function ReaderRolling:setupRerenderingAutomation()
         if self.rendering_state ~= prev_state then
             logger.dbg("_stepRerenderingAutomation", prev_state, ">", self.rendering_state)
             -- Have ReaderView redraw and refresh ReaderFlipping and our state icon, avoiding flashes
-            UIManager:setDirty(self.view.dialog, "ui", self.view.flipping.dimen)
+            UIManager:setDirty(self.view.dialog, "ui", self.view.flipping:getRefreshRegion())
         end
         if reschedule then
             UIManager:scheduleIn(1, self._stepRerenderingAutomation)