Fix base-path handling in key insert (#7775)

This fixes the handling of base-path when using `key insert`. Before
the base-path wasn't setup correctly, as done when starting a node. This
resulted in putting the keys into the wrong directory. This pr fixes
this by creating the correct base-path/config dir for the keystore.
Besides that it also removes the insert command from `subkey` as it
doesn't make that much sense. If requested, we could bring it back later.

substrate/client/cli/src/lib.rs

@@ -112,10 +112,7 @@ pub trait SubstrateCli: Sized {
 	///
 	/// Gets the struct from the command line arguments. Print the
 	/// error message and quit the program in case of failure.
-	fn from_args() -> Self
-	where
-		Self: StructOpt + Sized,
-	{
+	fn from_args() -> Self where Self: StructOpt + Sized {
 		<Self as SubstrateCli>::from_iter(&mut std::env::args_os())
 	}