Support for include files in shader_binary() rule

in `cc_binary()` I can just use `srcs` attribute:

```
cc_binary(name = "main", srcs = ["main.cc", "main.h"])
```

but `shader_binary` doesn't support includes.
It passes all `srcs` argument equally to `glslc` which errors out:

```
glslc: error: linking multiple files is not supported yet. Use -c to compile files individually.
```