VendorManifest and CompatibilityMatrix from and to XML.

Usage:

    #include <vintf/VendorManifest.h>
    #include <vintf/parse_xml.h>
    VendorManifest vm;
    // ...
    std::string xml = gVendorManifestConverter(vm);
    VendorManifest vm2;
    bool success = gVendorManifestConverter(&vm2, xml);
    if (!success)
        ALOGW("%s", gVendorManifestConverter.lastError());

See Vendor Interface Object and Compatibility Matrix Design
document and libvintf_test (test/main.cpp) for details.
(Up to commit 4468534)

Test: libvintf_test

Bug: 32648352

Change-Id: I7e8ee8d2b9e61bf036e77a390712480cbbd452b4
27 files changed