Add missing headers to runtime_cc target (#8492)

Transitive headers like array.h have not been available in the runtime_cc target causing the build to fail. Adding all public headers to make sure transitive headers of flatbuffers.h are available.

BUILD.bazel

@@ -121,15 +121,7 @@ filegroup(
 # Library used by flatbuffer_cc_library rules.
 cc_library(
     name = "runtime_cc",
-    hdrs = [
-        "include/flatbuffers/base.h",
-        "include/flatbuffers/flatbuffers.h",
-        "include/flatbuffers/flexbuffers.h",
-        "include/flatbuffers/stl_emulation.h",
-        "include/flatbuffers/util.h",
-        "include/flatbuffers/vector.h",
-        "include/flatbuffers/verifier.h",
-    ],
+    hdrs = ["//:public_headers"],
     linkstatic = 1,
     strip_include_prefix = "/include",
 )