Allow customizing WearRecoveryUI via Makefile variables.

With the following Makefile variables, we can reduce the work of writing
(copy/pasting) device-specific WearRecoveryUI classes.

The list of Makefile variables (the ones useful for Wear devices):
- TARGET_RECOVERY_UI_MARGIN_HEIGHT (default: 0)
- TARGET_RECOVERY_UI_MARGIN_WIDTH (default: 0)
  Specify the margin space that we don't want to display texts. They
  replace the former outer_width and outer_height.

- TARGET_RECOVERY_UI_TOUCH_LOW_THRESHOLD (default: 50)
- TARGET_RECOVERY_UI_TOUCH_HIGH_THRESHOLD (default: 90)
  Specify the sensitivity of recognizing a swipe. Devices give absolute
  positions, so for some devices we need to adjust the thresholds.

- TARGET_RECOVERY_UI_PROGRESS_BAR_BASELINE
  Specify the progress bar vertical position, which should be adjusted
  to the actual height of a device. It replaces the former
  progress_bar_y.

- TARGET_RECOVERY_UI_ANIMATION_FPS (default: 30)
  Specify the animation FPS if using device-specific animation images.
  It replaces the former animation_fps.

Devices can specify "TARGET_RECOVERY_UI_LIB := librecovery_ui_wear",
with optionally defined Makefile vars above, in BoardConfig.mk to
customize their WearRecoveryUI.

Also remove the obsolete wear_touch.{cpp,h}, which has been merged into
ui.cpp in commit 5f8dd9951d986b65d98d6a9ea38003427e9e46df.

Bug: 64307776
Test: Change the device BoardConfig.mk and test recovery image.
Change-Id: Id0fb2d4e3977ab5ddd31e71f9535470cab70e41b
(cherry picked from commit 0470ceea381775b09eee931858c3320be88cc637)