VintfObject: load ODM manifest and override vendor manifest

Priority for loading vendor manifest:

1. If {sku} sysprop is set and both files exist,
/vendor/etc/manifest.xml + /odm/etc/manifest_{sku}.xml

2. If both files exist,
/vendor/etc/manifest.xml + /odm/etc/manifest.xml

3. If file exists, /vendor/etc/manifest.xml

4. If {sku} sysprop is set and file exists,
/odm/etc/manifest_{sku}.xml

5. If file exists, /odm/etc/manifest.xml

6. If file exists, /vendor/manifest.xml

Test: vintf_object_tests
Bug: 69051162
Change-Id: Icf9e0353ad9da51f6105ee05fc07fa2348c5afa2
4 files changed