[beta] Backports (#8785)

* Fix light sync with initial validator-set contract (#8528)

* Fix #8468

* Use U256::max_value() instead

* Fix again

* Also change initial transaction gas

* Resumable warp-sync / Seed downloaded snapshots (#8544)

* Start dividing sync chain : first supplier method

* WIP - updated chain sync supplier

* Finish refactoring the Chain Sync Supplier

* Create Chain Sync Requester

* Add Propagator for Chain Sync

* Add the Chain Sync Handler

* Move tests from mod -> handler

* Move tests to propagator

* Refactor SyncRequester arguments

* Refactoring peer fork header handler

* Fix wrong highest block number in snapshot sync

* Small refactor...

* Resume warp-sync downloaded chunks

* Add comments

* Refactoring the previous chunks import

* Fix tests

* Address PR grumbles

* Fix not seeding current snapshot

* Address PR Grumbles

* Address PR grumble

* Retry failed CI job

* Update SnapshotService readiness check
Fix restoration locking issue for previous chunks restoration

* Fix tests

* Fix tests

* Fix test

* Early abort importing previous chunks

* PR Grumbles

* Update Gitlab CI config

* SyncState back to Waiting when Manifest peers disconnect

* Move fix

* Better fix

* Revert GitLab CI changes

* Fix Warning

* Refactor resuming snapshots

* Fix string construction

* Revert "Refactor resuming snapshots"

This reverts commit 75fd4b553a38e4a49dc5d6a878c70e830ff382eb.

* Update informant log

* Fix string construction

* Refactor resuming snapshots

* Fix informant

* PR Grumbles

* Update informant message : show chunks done

* PR Grumbles

* Fix

* Fix Warning

* PR Grumbles

* Don't open Browser post-install on Mac (#8641)

Since we start parity with the UI disabled per default now, opening the browser post installation will show an annoying error message, confusing the user. This patch removes opening the browser to prevent that annoyance.

fixes #8194

* Fix not downloading old blocks (#8642)

* Fix PoW blockchains sealing notifications in chain_new_blocks (#8656)

* Shutdown the Snapshot Service early (#8658)

* Shutdown the Snapshot Service when shutting down the runner

* Rename `service` to `client_service`

* Fix tests

* Fix cli signer (#8682)

* Update ethereum-types so `{:#x}` applies 0x prefix

* Set the request index to that of the current request (#8683)

* Set the request index to that of the current request

When setting up the chain of (two) requests to look up a block by hash, the second need to refer to the first. This fixes an issue where the back ref was set to the subsequent request, not the current one. When the requests are executed we loop through them in order and ensure the requests that should produce headers all match up. We do this by index so they better be right.

In other words: off by one.

* network-devp2p: handle UselessPeer disconnect (#8686)

* Fix local transactions policy. (#8691)

* CI: Fixes for Android Pipeline (#8745)

* ci: Remove check for shared libraries in gitlab script

* ci: allow android arm build to fail

* Custom Error Messages on ENFILE and EMFILE IO Errors (#8744)

* Custom Error Messages on ENFILE and EMFILE IO Errors

Add custom mapping of ENFILE and EMFILE IO Errors (Failure because of missing system resource) right when chaining ioError into ::util::Network::Error to improve Error Messages given to user

Note: Adds libc as a dependency to util/network

* Use assert-matches for more readable tests

* Fix Wording and consistency

* ethcore-sync: fix connection to peers behind chain fork block (#8710)