[Frame Core] Construct Runtime V2 follow-ups

[gupnik]

#1378 introduced the new runtime macro. This issue tracks the follow-up items:

• Remove the experimental flag once its tested in Rococo/Westend
• Abstract away the executive similar to Abstract away the executive substrate#14742
• Either support cfg attrs or throw an error if they should not be used CC: @ggwpez

[kianenigma]

Abstract away the executive similar to paritytech/substrate#14742

I am not sure about this. but it is a good candidate.

Alternatively, what I see missing rn is mostly that AllPallets is used in Type Executive but is never declared. Bringing it in scope might help.

I have also pointed out before that this macro seems to do some automatic use * that makes it not intuitive to use, and not in par with frame::pallet macro. Would be great if you can log this as well.

Here's my mentality:

You import polkadot-sdk-frame. This docs for this crate should be informative.

#[frame::pallet] 
pub mod pallet1 {
    use frame::pallet_prelude::*;
} 

#[frame::pallet] 
pub mod pallet2 {
    use frame::pallet_prelude::*;
}

#[cfg(test)]
pub mod tests {
    pub use frame::testing_prelude::*; 

    #[frame::runtime]
    pub mod runtime {
        use frame::runtime_prelude::*;
    }
}

So the experience and behavior you would get from all of these should be as similar as possible.

[gupnik]

I have also pointed out before that this macro seems to do some automatic use * that makes it not intuitive to use, and not in par with frame::pallet macro. Would be great if you can log this as well.

It actually maintains the same scope as with the previous CRV1. I can scope those under a mod and expose all of the generated types such as RuntimeEvent by default, but I am not sure if that adds a lot of value?

use frame::runtime_prelude::*;

What does this runtime_prelude provide?

[kianenigma]

What does this runtime_prelude provide?

Types that are needed for a typical runtime, the existing code should to some extent describe this

polkadot-sdk/substrate/frame/src/lib.rs

Lines 165 to 175 in fc07bda

	/// All of the types and tools needed to build FRAME-based runtimes.
	#[cfg(any(feature = "runtime", feature = "std"))]
	pub mod runtime {
	/// The main prelude of `FRAME` for building runtimes.
	///
	/// A runtime typically starts with:
	///
	/// ```
	/// use polkadot_sdk_frame::{prelude::*, runtime::prelude::*};
	/// ```
	pub mod prelude {