Make it accordance for occlum package name and extracted dir name

For example, in occlum_instance dir, do "occlum package occlum_test".
After extracting the occlum_test.tar.gz, we will get "occlum_test"
instead of "occlum_instance".

Signed-off-by: Zheng, Qi <huaiqing.zq@antgroup.com>

tools/occlum

@@ -440,7 +440,9 @@ cmd_package() {
         "
     fi
 
-    cd .. && tar -cvzf $instance_dir/$package_name $pkg_files $sim_files
+    cd .. && tar -cvzf $instance_dir/$package_name \
+                --transform s/$instance_base_name/$(basename $package_name .tar.gz)/ \
+                $pkg_files $sim_files
 
     echo "The package $package_name is generated successfully"
 }