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/frame/contracts/rpc/Cargo.toml

@@ -5,11 +5,11 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 
 [dependencies]
-client = { package = "substrate-client", path = "../../../client/" }
 codec = { package = "parity-scale-codec", version = "1.0.0" }
 jsonrpc-core = "14.0.3"
 jsonrpc-core-client = "14.0.3"
 jsonrpc-derive = "14.0.3"
+sp-blockchain = { path = "../../../primitives/blockchain" }
 primitives = { package = "substrate-primitives",  path = "../../../primitives/core" }
 rpc-primitives = { package = "substrate-rpc-primitives", path = "../../../primitives/rpc" }
 serde = { version = "1.0.101", features = ["derive"] }

substrate/frame/contracts/rpc/src/lib.rs

@@ -18,7 +18,7 @@
 
 use std::sync::Arc;
 
-use client::blockchain::HeaderBackend;
+use sp_blockchain::HeaderBackend;
 use codec::Codec;
 use jsonrpc_core::{Error, ErrorCode, Result};
 use jsonrpc_derive::rpc;