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/db/Cargo.toml

@@ -23,7 +23,7 @@ executor = { package = "substrate-executor", path = "../executor" }
 state_db = { package = "substrate-state-db", path = "../state-db" }
 trie = { package = "substrate-trie", path = "../../primitives/trie" }
 consensus_common = { package = "substrate-consensus-common", path = "../../primitives/consensus/common" }
-header_metadata = { package = "substrate-header-metadata", path = "../header-metadata" }
+sp-blockchain = { path = "../../primitives/blockchain" }
 
 [dev-dependencies]
 substrate-keyring = { path = "../../primitives/keyring" }