Improved the Build subcommand to support the building of Docker images (#11)

This PR contains the work done to support the building of Docker images in the `Build` subcommand in the executable target. So, for this purpose, the following task have been done:

- added a basic boilerplate of the `docker-compose.yml` file;
- fixed some issues found in the boilerplate of the `Dockerfile` file;
- defined the `Randomable` protocol;
- defined the `Artifact` enumeration;
- updated the `BuildProjectTask` task to support building Docker images if required;
- renamed the `BuildProjectTask` task as `BuildArtifactTask`.

Reviewed-on: #11
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Library/Sources/Internal/Protocols/Randomable.swift

@@ -0,0 +1,7 @@
+protocol Randomable: CaseIterable {
+    
+    // MARK: Functions
+    
+    static func random() -> Self
+    
+}