Use semantic versioning for the public CD container image

[lionello]

To ensure that the CLI code expectations match the deployed infra.

[lionello]

CLI hardcoded to pick the latest version for a major version number, ie. "v1", "v2" etc.. CD updates would get pushed to the major version, so that older CLIs would not get breaking changes.

[lionello]

Even more important for DigitalOcean where the cd:latest did not get refetched and was referring to a 2 month old image without latest changes.

[nullfunc]

Description:

• The public cd is used in BYOC to create and deploy applications.
• Each customer project needs to be built and deployed on to their provider.
• Each project image is tied to a cd version as there may be some resource assignments/configurations or gRPC changes unique to that cd and expected by the application when it was built.
• cd gets updated regularly and may introduce breaking changes which make it incompatible with deployment of already deployed projects. Breaking change update the cd's major version. Non-breaking changes will update the minor version numbers.

Use Cases: Goal is to adding a mechanism to reliably bump the public-cd image and make sure the CLI is using a specific version. Customers with existing deployments will continue to use that major cd version but new stacks will use the latest.

• When re-deploying an project without any project source changes we wish to deploy without building and use a cd image with the same major number version as the cd used to build/release the last project image.
• When deploying for the first time ~~or after project source changes~~ the images will be built and deployed with the latest cd
• We are moving to a new pulumi provider, all stacks will be updated. Any existing projects (stacks) would not expect to have to tear down and re-deploy a new stack when they make changes so they should continue to update using the specific cd (major numbers version).
• Stop using latest on cd images and use major/minor. We can guarantee that the CLI is using a specific major/minor version of a public-cd so they have consistent behaviour of their stack.

Work Items:

• Tag each public cd image with a semver. Keep track of the latest semver and increase minor/patch per update of the cd image (use defang-mvp/pulumi/package.json for version tracking)
• Each project has a project.pb which is generated from the proto which is loaded in the CLI byoc.go. We should add a cd-version into into the protobuf. When it's read in the CLI it should direct the CLI to use a specific cd version. ~~- update CLI use the latest major version of cd for projects needing rebuild~~
• update CLI, when deploying an existing project image use the latest non-breaking cd version that the project image was built with

@lionello @edwardrf Could you comment on this? I want to make sure the description, use case, and work items are accurate on what this issue will address and how.