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>

Test/Sources/Cases/Internal/Enumerations/FileTests.swift

@@ -56,6 +56,7 @@ private extension FileTests {
             "AppArguments.swift",
             "AppBuilder.swift",
             "AppOptions.swift",
+            "docker-compose.yml",
             "Dockerfile",
             ".dockerignore",
             "Environment+Properties.swift",
@@ -70,6 +71,7 @@ private extension FileTests {
             "Library/Sources/Public/AppArguments.swift",
             "Library/Sources/Public/AppBuilder.swift",
             "App/Sources/AppOptions.swift",
+            "docker-compose.yml",
             "Dockerfile",
             ".dockerignore",
             "Library/Sources/Internal/Environment+Properties.swift",
@@ -86,6 +88,7 @@ private extension FileTests {
             .app,
             .root,
             .root,
+            .root,
             .libraryInternal,
             .root,
             .root,
@@ -100,6 +103,7 @@ private extension FileTests {
             "Resources/Files/Sources/App",
             "Resources/Files/Sources",
             "Resources/Files/Sources",
+            "Resources/Files/Sources",
             "Resources/Files/Sources/Library",
             "Resources/Files/Sources",
             "Resources/Files/Sources",