Vendor apex sets "vndkVersion" when it uses vndk libs

Vendor apex with "use_vndk_as_stable:true" sets the dependency in
"requireNativeLibs: ":vndk"". But this isn't enough because the APEX
won't work if VNDK version mismatches.

Now, when a vendor apex uses VNDK libs, "vndkVersion" is set as well in
apex_manifest so that apexd can abort the installation/staging when
device's VNDK version mimatches.

Bug: 222620439
Test: VendorApexHostTestCases
Test: built vendor apex how has "vndkVersion" field in its
 apex_manifest
Change-Id: If03340c230efe854ab932cdf472c276f7646ad0c