SystemUI: implement better partial screenshot

commit ecd79bcd1362bf81b0ce0dfc970c3a7cef7a459e
Author: Demon000 <demonsingur@gmail.com>
Date:   Mon Jan 20 03:37:29 2020 +0000

    ScreenshotHelper: ignore timeout when taking partial screenshots

    User should have as much time to select the region as he wants.

    Change-Id: Ib9b79d5127a59d3e2af278dbc8cd054221c37ca6

commit 39b2b0fa8979b2904d7435215cd13241a9ca296e
Author: ezio84 <brabus84@gmail.com>
Date:   Sun Dec 1 18:19:48 2019 +0100

    SystemUI: block gestural navigation when using partial screenshot

    Change-Id: I68d25a6eab9ea16707e8736b9e56055532bcdf87

commit 77d3a89ebde978c195b4623fa3fbc52b75975f32
Author: Demon000 <demonsingur@gmail.com>
Date:   Sat Feb 1 18:24:34 2020 +0000

    GlobalScreenshot: do not capture multiple screenshots simultaneously

    Change-Id: I4c0c73759b8b0483f0d28b4c6c39e9a616c26b57

Change-Id: Ib818b24bb788a19ac210378611402c96fa55bd37