Add link to the weight comparison tool for weights PRs (#1788)

* add link to the weight comparison tool for weights PRs

* Update scripts/create-benchmark-pr.sh

Co-authored-by: Chevdor <chevdor@users.noreply.github.com>

* add backport checklist item

* move to scripts/ci

Co-authored-by: Chevdor <chevdor@users.noreply.github.com>

scripts/ci/create-benchmark-pr.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+
+set -Eeu -o pipefail
+shopt -s inherit_errexit
+
+PR_TITLE="$1"
+HEAD_REF="$2"
+
+ORG="paritytech"
+REPO="$CI_PROJECT_NAME"
+BASE_REF="$CI_COMMIT_BRANCH"
+# Change threshold in %. Bigger values excludes the small changes.
+THRESHOLD=${THRESHOLD:-30}
+
+WEIGHTS_COMPARISON_URL_PARTS=(
+  "https://weights.tasty.limo/compare?"
+  "repo=$REPO&"
+  "threshold=$THRESHOLD&"
+  "path_pattern=**%2Fweights%2F*.rs&"
+  "method=guess-worst&"
+  "ignore_errors=true&"
+  "unit=time&"
+  "old=$BASE_REF&"
+  "new=$HEAD_REF"
+)
+printf -v WEIGHTS_COMPARISON_URL %s "${WEIGHTS_COMPARISON_URL_PARTS[@]}"
+
+PAYLOAD="$(jq -n \
+  --arg title "$PR_TITLE" \
+  --arg body "
+This PR is generated automatically by CI.
+
+Compare the weights with \`$BASE_REF\`: $WEIGHTS_COMPARISON_URL
+
+- [ ] Backport to master and node release branch once merged
+" \
+  --arg base "$BASE_REF" \
+  --arg head "$HEAD_REF" \
+  '{
+      title: $title,
+      body: $body,
+      head: $head,
+      base: $base
+   }'
+)"
+
+echo "PAYLOAD: $PAYLOAD"
+
+curl \
+  -H "Authorization: token $GITHUB_TOKEN" \
+  -X POST \
+  -d "$PAYLOAD" \
+  "https://api.github.com/repos/$ORG/$REPO/pulls"