cc_fuzz: add "data" field

"data" field specifies data dependencies that will be installed in
fuzzer's output directory.

"data" behaves similar to "corpus", except "data" preserves directory
structure, e.g.

    data: ["foo/bar.txt"]

is installed into

    $OUT/data/fuzz/<arch>/<target>/data/foo/bar.txt

Test: build a fuzzer with data depenency, check data is installed
correctly
Change-Id: Ia1255026278435181b6d93f91f8f9ad39c96d07f