Add a debug flag to validate schema reflection

When the flag is set, after every DDL command we reintrospect the
database and compare that to the in-meory schema. I've recently landed
a few PRs fixing issues exposed by this. (IIRC, I also fixed a few
earlier this year when I first wrote this PR.) Overall the system is
pretty solid.

Run it in CI once a day, since I think it is too slow to run all the
time.

Fixes #5169.

.github/Makefile

@@ -13,7 +13,8 @@ all: workflows/nightly.yml \
 	workflows/tests-ha.yml \
 	workflows/tests-pg-versions.yml \
 	workflows/tests-patches.yml \
-	workflows/tests-inplace.yml
+	workflows/tests-inplace.yml \
+	workflows/tests-reflection.yml \
 
 workflows/%.yml: workflows.src/%.tpl.yml workflows.src/%.targets.yml workflows.src/build.inc.yml workflows.src/ls-build.inc.yml
 	$(ROOT)/workflows.src/render.py $* $*.targets.yml
@@ -38,3 +39,6 @@ workflows.src/tests-patches.tpl.yml: workflows.src/tests.inc.yml
 
 workflows.src/tests-inplace.tpl.yml: workflows.src/tests.inc.yml
 	touch $(ROOT)/workflows.src/tests-inplace.tpl.yml
+
+workflows.src/tests-reflection.tpl.yml: workflows.src/tests.inc.yml
+	touch $(ROOT)/workflows.src/tests-inplace.tpl.yml

.github/workflows.src/tests-reflection.targets.yml

@@ -0,0 +1 @@
+data:

.github/workflows.src/tests-reflection.tpl.yml

@@ -0,0 +1,59 @@
+<% from "tests.inc.yml" import build, calc_cache_key, restore_cache -%>
+name: Tests with reflection validation
+
+on:
+  schedule:
+    - cron: "0 3 * * *"
+  workflow_dispatch:
+    inputs: {}
+  push:
+    branches:
+      - "REFL-*"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    <%- call build() -%>
+
+    - name: Compute cache keys
+      env:
+        GIST_TOKEN: ${{ secrets.CI_BOT_GIST_TOKEN }}
+      run: |
+        << calc_cache_key()|indent >>
+    <%- endcall %>
+
+  test:
+    needs: build
+    runs-on: ubuntu-latest
+
+    steps:
+    <<- restore_cache() >>
+
+    # Run the test
+
+    - name: Test
+      env:
+        EDGEDB_TEST_REPEATS: 1
+      run: |
+        edb test -j2 -v
+
+  workflow-notifications:
+    if: failure() && github.event_name != 'pull_request'
+    name: Notify in Slack on failures
+    needs:
+      - build
+      - test
+    runs-on: ubuntu-latest
+    permissions:
+      actions: 'read'
+    steps:
+      - name: Slack Workflow Notification
+        uses: Gamesight/slack-workflow-status@26a36836c887f260477432e4314ec3490a84f309
+        with:
+          repo_token: ${{secrets.GITHUB_TOKEN}}
+          slack_webhook_url: ${{secrets.ACTIONS_SLACK_WEBHOOK_URL}}
+          name: 'Workflow notifications'
+          icon_emoji: ':hammer:'
+          include_jobs: 'on-failure'