Consolidate frame benchmarking into a frame crate (#4977)

This prs cleans up some of the frame benchmarking stuff:
- Move CLI into `frame-benchmarking-cli`. No frame related CLI should
exists in the default Substrate CLI.
- Move all traits and types related to frame benchmarking into the
`frame-benchmarking` trait. Frame types should be isolated in Frame.

substrate/bin/node/cli/src/cli.rs

@@ -53,6 +53,13 @@ pub enum Subcommand {
 		about = "Decode given block or extrinsic using current native runtime."
 	)]
 	Inspect(node_inspect::cli::InspectCmd),
+
+	/// The custom benchmark subcommmand benchmarking runtime pallets.
+	#[structopt(
+		name = "benchmark",
+		about = "Benchmark runtime pallets."
+	)]
+	Benchmark(frame_benchmarking_cli::BenchmarkCmd),
 }
 
 /// The `factory` command used to generate transactions.