Add cache warm and cache evict workflows

.github/workflows/cache-evict.yml

@@ -0,0 +1,57 @@
+name: Evict caches for merged PRs
+
+# Caches for merged PRs stay around until we bump against our cache limit.
+# They are also not shareable between branches. Therefore, once a PR is
+# merged, the cache for that branch is immediately not needed anymore, and we
+# can remove it. If we remove these caches, we can save space and be more sure
+# that the remaining caches are actually useful, and not at danger of being
+# evicted.
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+
+concurrency:
+  group: "cache-evict"
+  cancel-in-progress: true
+
+jobs:
+  evict-cache:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Evict caches
+        shell: bash
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+
+        # This script lists all caches for the repository, lists all remote refs
+        # for the repository, and then finds the caches that are not present in
+        # the remote refs. It then deletes those caches.
+        #
+        # For that, it uses the `gh` CLI to list and delete caches, and `git` to
+        # list remote refs. It also uses `jq` to manipulate the data as JSON.
+        # (It's surprisingly difficult to find a shell command to check if a
+        # string is inside a given array, that's why we use `jq`.)
+        run: |
+          (
+            # Input 0: List all caches for the repository
+            gh cache list --limit 100 --json key,ref
+
+            # Input 1: List all remote refs for the repository, do some string
+            # manipulation to get the ref names (second column) as a JSON array
+            git ls-remote "https://github.com/$GITHUB_REPOSITORY.git" |
+              awk '{print $2}' |
+              jq --raw-input --compact-output '.' |
+              jq --slurp '.'
+          ) |
+            # Find cache refs not present in the remote refs, and extract their keys
+            jq --slurp --raw-output \
+              '.[0] as $caches | .[1] as $remote_refs | $caches.[] | select([.ref] | inside($remote_refs) | not) | .key' |
+            while read -r key; do
+              # Delete those cache keys
+              gh cache delete "$key" ||
+                echo "::warning::Failed to delete cache key $key"
+            done

.github/workflows/cache-warm.yml

@@ -0,0 +1,18 @@
+name: Keeps build cache warm
+
+on:
+  workflow_dispatch:
+  schedule:
+    # GitHub evicts unused caches after 7 days, so we run this every 6 days
+    - cron: "0 0 */6 * *"
+
+concurrency:
+  group: "cache-warm"
+  cancel-in-progress: false
+
+jobs:
+  warm-cache-build:
+    uses: ./.github/workflows/waspc-build.yaml
+
+  warm-cache-ci:
+    uses: ./.github/workflows/waspc-ci.yaml

.github/workflows/deploy-examples.yml

@@ -25,6 +25,9 @@ concurrency:
   group: "deploy-examples"
   cancel-in-progress: true
 
+env:
+  WASP_TELEMETRY_DISABLE: 1
+
 jobs:
   deploy:
     strategy: