Move CI from GitHub Actions to GitLab (#814)

* CI: do not trust this CI 1

* CI: don't want to trigger unneded statuses

* CI: debug 1

* CI: new CI

* CI: temp allow failure

* CI: exclude paths

* doc: check if docs won't trigger pipelines

* doc: check hybrid changes pipeline

* doc: do not push excluded files together with others

* CI: undebug fmt

* CI: better deny

* CI: fix deny and spellcheck

* CI: global backtrace

* CI: deny config

* CI: publishing

* Dockerfile: metadata fix [skip ci]

* CI: revert me

* CI: debug bash

* CI: mv ci.Dockerfile; fix buildah bug

* CI: fix artifact name

* Dockerfile: fix context

* CI: separate deny check licenses

* CI: when to run

* CI: unneded stuff in these Dockerfiles

* CI: merged test-refs and build-refs

* CI: test-build optimizations

* CI: changes, web, scheduled pipelines now work as intended

* CI: use tested production CI image

* CI: substitute GHA

* Fix clippy.

* Moar clippy fixes.

* Fix more.

* Finally fix all?

Co-authored-by: Tomasz Drwięga <tomasz@parity.io>

bridges/README.md

@@ -24,14 +24,14 @@ Substrate chains or Ethereum Proof-of-Authority chains.
 To get up and running you need both stable and nightly Rust. Rust nightly is used to build the Web
 Assembly (WASM) runtime for the node. You can configure the WASM support as so:
 
-```
+```bash
 rustup install nightly
 rustup target add wasm32-unknown-unknown --toolchain nightly
 ```
 
 Once this is configured you can build and test the repo as follows:
 
-```
+```bash
 git clone https://github.com/paritytech/parity-bridges-common.git
 cd parity-bridges-common
 cargo build --all
@@ -49,7 +49,7 @@ and external processes called relayers. A bridge chain is one that is able to fo
 of a foreign chain independently. For example, consider the case below where we want to bridge two
 Substrate based chains.
 
-```
+```bash
 +---------------+                 +---------------+
 |               |                 |               |
 |     Rialto    |                 |    Millau     |
@@ -77,7 +77,7 @@ Here's an overview of how the project is laid out. The main bits are the `node`,
 "blockchain", the `modules` which are used to build the blockchain's logic (a.k.a the runtime) and
 the `relays` which are used to pass messages between chains.
 
-```
+```bash
 ├── bin             // Node and Runtime for the various Substrate chains
 │  └── ...
 ├── deployments     // Useful tools for deploying test networks
@@ -103,6 +103,7 @@ To run the Bridge you need to be able to connect the bridge relay node to the RP
 on each side of the bridge (source and target chain).
 
 There are 3 ways to run the bridge, described below:
+
 - building & running from source,
 - building or using Docker images for each individual component,
 - running a Docker Compose setup (recommended).