ci: create helpers for formatting errors and notices

Create helpers for formatting errors and notices for GitHub actions,
instead of directly printing the double colons and attributes.

travis-ci/vmtest/helpers.sh

@@ -24,3 +24,23 @@ travis_fold() {
 }
 
 ARCH=$(uname -m)
+
+__print() {
+  local TITLE=""
+  if [[ -n $2 ]]; then
+      TITLE=" title=$2"
+  fi
+  echo "::$1${TITLE}::$3"
+}
+
+# $1 - title
+# $2 - message
+print_error() {
+  __print error $1 $2
+}
+
+# $1 - title
+# $2 - message
+print_notice() {
+  __print notice $1 $2
+}