Add <vendor-ndk> tag to fwk manifest and device matrix

... in place of the old <vndk> tag. The format of this tag is:

- in framework manifest: a string (a number, or VERSION_CODE during
development):
<vendor-ndk>
    <version>27</version>
</vendor-ndk>
<vendor-ndk>
    <version>P</version>
</vendor-ndk>

- in device matrix: same format, but only one <vendor-ndk> tag.
<vendor-ndk>
    <version>27</version>
</vendor-ndk>

Test: libvintf_test
Bug: 36400653
Change-Id: If235e257026d719838076bf0e0a2b42aa8524971
9 files changed