add deploy-sourcegraph-dhall pipeline to deploy-sourcegraph-dot-com

[ggilmore]

Part of: #13340

Depends on: #14131, #14130, #13338, #14133, #17631, #17290

MVP for this work is a pipeline that deploys symbols

• deploy-sourcegraph-dot-com-pipeline.dhall generates a Dhall record containing only symbols component
• ds-to-dhall dhall2ds used to convert to K8s compatible yaml
• Open source Dhall repo to allow us to add a generate.dhall file into deploy-sourcegraph-dot-com
• Add pipeline.dhall file that imports https://github.com/sourcegraph/deploy-sourcegraph-dhall with the necessary customizations
• Remove existing https://github.com/sourcegraph/deploy-sourcegraph-dot-com YAML files for symbols, gitserver
• YAML is committed back to branch automatically via pipeline tool (in the correct place)
• Renovate should not modify the symbol's k8s yaml. It should operate on the deploy-sourcegraph-dot-com-pipeline.dhall sourcegraph.com: write bot to incorporate image tag updates in dhall pipeline #14133
• Add CI check to verify that dhall and generated kubernetes YAML are synchronized (runs every commit)

[daxmc99]

TODO:

• dhall diff '(./src/k8s/pipeline-dot-com.dhall).repo-updater' '(./deploy-sourcegraph-dot-com.dhall).repo-updater'
• github-proxy
• symbols

[daxmc99]

Deep dive into a renovate PR:

• When Renovate creates a PR to update an image it should

1. Choose the correct file to use, update a renovate-compatible file renovateHERE.yaml representation of all images
2. Workflow triggers to dhall-to-yaml | yaml-to-k8s & commit back to branch
3. After CI passes, merge

[pecigonzalo]

Removing from the current iteration as we shift priorities.

[github-actions]

Heads up @davejrt @ggilmore @dan-mckean @caugustus-sourcegraph @StephanX - the "team/delivery" label was applied to this issue.

[daxmc99]

Not currently pursing