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/src/light/backend.rs

@@ -26,6 +26,7 @@ use primitives::offchain::storage::InMemOffchainStorage;
 use sr_primitives::{generic::BlockId, Justification, StorageOverlay, ChildrenStorageOverlay};
 use sr_primitives::traits::{Block as BlockT, NumberFor, Zero, Header};
 use crate::in_mem::{self, check_genesis_storage};
+use sp_blockchain::{ Error as ClientError, Result as ClientResult };
 use client_api::{
 	backend::{
 		AuxStore, Backend as ClientBackend, BlockImportOperation, RemoteBackend, NewBlockState,
@@ -34,9 +35,6 @@ use client_api::{
 	blockchain::{
 		HeaderBackend as BlockchainHeaderBackend, well_known_cache_keys,
 	},
-	error::{
-		Error as ClientError, Result as ClientResult
-	},
 	light::Storage as BlockchainStorage,
 };
 use crate::light::blockchain::Blockchain;