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/primitives/sr-api/test/tests/decl_and_impl.rs

@@ -18,7 +18,8 @@ use sr_api::{RuntimeApiInfo, decl_runtime_apis, impl_runtime_apis};
 
 use sr_primitives::{traits::{GetNodeBlockType, Block as BlockT}, generic::BlockId};
 
-use test_client::{client::error::Result, runtime::Block};
+use test_client::runtime::Block;
+use sp_blockchain::Result;
 
 /// The declaration of the `Runtime` type and the implementation of the `GetNodeBlockType`
 /// trait are done by the `construct_runtime!` macro in a real runtime.