ADB Backup: fix adb restore issues

Set Backup_FileName on adb backup to fix restore.
Set read_from_adb after EOF to return properly
from newer adb client prompt.
Create setter and getter for Backup_FileName
for openrecoveryscript.cpp which is not a
friend class.
Fix condition for twrpTar::Get_Size() and adb backup.
Change-Id: I7eb8168fa3416366b996e220cecbc0e1bcec5e8e
diff --git a/twrpTar.cpp b/twrpTar.cpp
index 3911733..d86e133 100644
--- a/twrpTar.cpp
+++ b/twrpTar.cpp
@@ -1463,7 +1463,7 @@
 }
 
 unsigned long long twrpTar::get_size() {
-	if (TWFunc::Path_Exists(tarfn) && !part_settings->adbbackup) {
+	if (part_settings->adbbackup || TWFunc::Path_Exists(tarfn)) {
 		LOGINFO("Single archive\n");
 		return uncompressedSize(tarfn);
 	} else {