vmtests: add log folding

Sprinkle log folds around, including timing.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

travis-ci/vmtest/helpers.sh

@@ -0,0 +1,12 @@
+# $1 - start or end
+# $2 - fold identifier, no spaces
+# $3 - fold section description
+travis_fold() {
+	local YELLOW='\033[1;33m'
+	local NOCOLOR='\033[0m'
+	echo travis_fold:$1:$2
+	if [ ! -z "${3:-}" ]; then
+		echo -e "${YELLOW}$3${NOCOLOR}"
+	fi
+	echo
+}