Vulkan: Rename vk::LineLoopHelper. This more closely follows the general pattern laid out by the naming in vk_helpers.h. It also changes the dynamic buffer that the helper wraps to be stored by-value since the header include order problem is fixed. Bug: angleproject:2318 Change-Id: I1de9e1edee2125d3afd490b4f9c99cf70c61215c Reviewed-on: https://chromium-review.googlesource.com/1001654 Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>