Start GH Action workflow for automation

Currently just runs the ingest workflow and uploads the results
to AWS S3. Subsequent commits will add automation for the phylogenetic
workflow.

.github/workflows/ingest-to-phylogenetic.yaml

@@ -0,0 +1,31 @@
+name: Ingest to phylogenetic
+
+on:
+  workflow_dispatch:
+
+jobs:
+  ingest:
+    permissions:
+      id-token: write
+    uses: nextstrain/.github/.github/workflows/pathogen-repo-build.yaml@master
+    secrets: inherit
+    with:
+      # Starting with the default docker runtime
+      # We can migrate to AWS Batch when/if we need to for more resources or if
+      # the job runs longer than the GH Action limit of 6 hours.
+      runtime: docker
+      run: |
+        nextstrain build \
+          --env AWS_ACCESS_KEY_ID \
+          --env AWS_SECRET_ACCESS_KEY \
+          ingest \
+            upload_all \
+            --configfile build-configs/nextstrain-automation/config.yaml
+      # Specifying artifact name to differentiate ingest build outputs from
+      # the phylogenetic build outputs
+      artifact-name: ingest-build-output
+      artifact-paths: |
+        ingest/results/
+        ingest/benchmarks/
+        ingest/logs/
+        ingest/.snakemake/log/