Remove all (non-dev) client references from frame, activate dependency enforcer (#4184)

* Move transaction pool to primitives

* move backend, errors into primitives

* remove unused client depencies

* Move rpc-api into primitives

* Move peerset back to client

* Move rpc/api back to client, move palette/support/rpc into utils

* move support-rpc into subfolder

* move system-rpc into utils

* move transaction-pool  and -graph back into client

* fix broken imports

* Clean up test primitives

* Make support test utils independent of frame

* remove unnecessary node dependencies from service

* Reactivate dependency script:
 - only enforce the now achieved status quo will remain
 - allow for primitives to depend on /client for now without failing
 - more discriptive error message so people understand, what it wants
 - minor fix to differentiative between ../client and /client (which may be a subfolder)
 - don't allow this to fail anylonger.

* fix doc comment

* 'Should not' rather than 'must not'.

* Revert unwanted dependency changes

* fix faulty import

* fixup derive_more version

* fix wrong import path

substrate/client/rpc/src/state/state_full.rs

@@ -28,7 +28,8 @@ use rpc::{
 };
 
 use api::Subscriptions;
-use client_api::{backend::Backend, error::Result as ClientResult};
+use client_api::backend::Backend;
+use sp_blockchain::Result as ClientResult;
 use client::{
 	Client, CallExecutor, BlockchainEvents, 
 };
@@ -232,7 +233,7 @@ impl<B, E, Block, RA> StateBackend<B, E, Block, RA> for FullState<B, E, Block, R
 		RA: Send + Sync + 'static,
 		Client<B, E, Block, RA>: ProvideRuntimeApi,
 		<Client<B, E, Block, RA> as ProvideRuntimeApi>::Api:
-			Metadata<Block, Error = client::error::Error>,
+			Metadata<Block, Error = sp_blockchain::Error>,
 {
 	fn call(
 		&self,