Add a --with_frames argument to fetch

When set (defaults to not set/false), --dump will include iframe contents.

I was hoping I could add a mode to strip_mode to this, but since dump is used
extensively (e.g. innerHTML), this is something that has to be off by default
(for correctness).

src/lightpanda.zig

@@ -36,7 +36,7 @@ const IS_DEBUG = @import("builtin").mode == .Debug;
 
 pub const FetchOpts = struct {
     wait_ms: u32 = 5000,
-    dump: dump.RootOpts,
+    dump: dump.Opts,
     dump_mode: ?Config.DumpFormat = null,
     writer: ?*std.Io.Writer = null,
 };