updater: Fix the wrong return value for package_extract_file().

'bool success = ExtractEntryToFile()' gives opposite result. Fix the
issue and add testcases.

Change the one-argument version of package_extract_file() to explicitly
abort for non-existent zip entry. Note that this is NOT changing the
behavior. Prior to this CL, it aborts from Evaluate() function, by
giving a general cause code. Now it returns kPackageExtractFileFailure.

BUg: 32903624
Test: recovery_component_test works.

Change-Id: I7a273e9c0d9aaaf8c472b2c778f7b8d90362c24f
(cherry picked from commit ef0eb3b01b)

tests/unit/zip_test.cpp

@@ -30,9 +30,6 @@
 
 #include "common/test_constants.h"
 
-static const std::string kATxtContents("abcdefghabcdefgh\n");
-static const std::string kBTxtContents("abcdefgh\n");
-
 TEST(ZipTest, ExtractPackageRecursive) {
   std::string zip_path = from_testdata_base("ziptest_valid.zip");
   ZipArchiveHandle handle;