Make frame crate not use the feature experimental

[gui1117]

We already use it for lots of pallet.

Keeping it feature gated by experimental means we lose the information of which pallet was using experimental before the migration to frame crate usage.

We can consider polkadot-sdk-frame crate unstable but let's not use the feature experimental.

[gui1117]

/cmd prdoc --audience runtime_dev --bump minor

[bkchr]

We should remove the feature from the Cargo.toml file and its usage everywhere. Otherwise this pr is not complete.

[re-gius]

We should remove the feature from the Cargo.toml file and its usage everywhere. Otherwise this pr is not complete.

Yes! You can find the merged PRs (and so the affected pallets) at #6504

[gui1117]

We should remove the feature from the Cargo.toml file and its usage everywhere. Otherwise this pr is not complete.

Yes, I removed usages of experimental when not needed in some crates and also in doc.

About removing the feature in frame crate itself, I think we can keep it, I agree it is not good that the feature will get enabled everywhere if one dependency enables it. One way to solve this would be to also have a disable_experimental feature which would check at compilation that the feature is not enabled.

Maybe instead of feature we should give the experimental nature in the type name like UnstableMaybeConsideration instead of MaybeConsideration.