Use magiskboot to repack the boot partition

Set TW_INCLUDE_REPACKTOOLS := true

Must also have:
AB_OTA_UPDATER := true

Use magiskboot and provide GUI options to allow users to repack
their existing boot image to install TWRP (or kernels) so we can
stop having to provide installation zips for AB devices. There is
also an option to try to fix a recovery bootloop if the kernel
has been patched to always boot the ramdisk for root, etc.

You will need to pull the below repo into external/magisk-prebuilt
https://github.com/TeamWin/external_magisk-prebuilt

Change-Id: I74196cc6f095a7576d61886dc96cbc18deba9b04
diff --git a/gui/theme/common/languages/en.xml b/gui/theme/common/languages/en.xml
index e61f6c0..7a60120 100755
--- a/gui/theme/common/languages/en.xml
+++ b/gui/theme/common/languages/en.xml
@@ -486,6 +486,28 @@
 		<string name="install_cancel">Do Not Install</string>
 		<string name="sel_storage_list">Select Storage</string>
 		<string name="ok_btn">OK</string>
+		<string name="install_twrp_ramdisk">Install Recovery Ramdisk</string>
+		<string name="install_kernel">Install Kernel</string>
+		<string name="repack_kernel_confirm_hdr">Install Kernel</string>
+		<string name="repack_ramdisk_confirm_hdr">Install Recovery</string>
+		<string name="repack_kernel_confirm">Install Kernel?</string>
+		<string name="repack_ramdisk_confirm">Install Recovery?</string>
+		<string name="repack_backup_first">Back up existing image first</string>
+		<string name="repack">Repack</string>
+		<string name="swipe_to_install">Swipe to Install</string>
+		<string name="installing">Installing...</string>
+		<string name="install_complete">Install Complete</string>
+		<string name="unpack_error">Error unpacking image.</string>
+		<string name="repack_error">Error repacking image.</string>
+		<string name="unpacking_image">Unpacking {1}...</string>
+		<string name="repacking_image">Repacking {1}...</string>
+		<string name="repack_image_hdr">Select Image</string>
+		<string name="fix_recovery_loop">Fix Recovery Bootloop</string>
+		<string name="fix_recovery_loop_confirm">Fix Recovery Bootloop?</string>
+		<string name="fixing_recovery_loop">Fixing Recovery Bootloop...</string>
+		<string name="fix_recovery_loop_complete">Fix Recovery Bootloop Complete</string>
+		<string name="fixing_recovery_loop_patch">Patching kernel...</string>
+		<string name="fix_recovery_loop_patch_error">Error patching kernel.</string>
 
 		<!-- Various console messages - these consist of user displayed messages, oftentimes errors -->
 		<string name="no_kernel_selinux">Kernel does not have support for reading SELinux contexts.</string>