Dockerfile definition and helper scripts related to preparing a toolchain image able to produce WASM binaries

Includes emscripten toolchain like also precompiled libraries:

• boost
• openssl
• sec256k1-zkp

.gitlab-ci.yml

@@ -75,7 +75,7 @@ lint_python_scripts:
 
 .build_docker_image:
   extends: .docker_image_builder_job_template
-  image: docker:20.10.21
+  image: docker:24.0.1-cli
   variables:
     BUILD_TARGET: ""
   before_script:
@@ -111,7 +111,7 @@ build_docker_dind_image:
       exists:
         - Dockerfile.docker-dind
   services:
-    - docker:20.10.21-dind
+    - docker:24.0.1-dind
 
 build_docker_builder_image:
   extends: .build_docker_image