rework the build system

- use rustls for reqwest, so we don't need to compile OpenSSL
- use better defaults for build arguments in Dockerfile
- add Continuous Integration workflow for master branch and it's pull requests
- add Release workflow for tags matching SemVer
- add release template for automatic release notes generation with GH CLI
- remove old and unused assets under .github

.github/scripts/compress-artifact.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+BINARY_FILE="target/$1/release/sculptor"
+COMMON_FILES=("Config.example.toml")
+ARTIFACT_OUTPUT="${OUTPUT_DIR}/sculptor-$2-$3"
+if [ "$2" = "windows" ]
+then zip -j "${ARTIFACT_OUTPUT}.zip" "${BINARY_FILE}.exe" "${COMMON_FILES[@]}"
+else tar --transform 's|^.*/||' -czf "${ARTIFACT_OUTPUT}.tar.gz" "$BINARY_FILE" "${COMMON_FILES[@]}"
+fi