Add ability for azd deploy to bypass container image push

[peterharding93]

Suggestion:

Ability to execute something like:
azd deploy --skip-container-push

I feel this will greatly improve productivity for developers trying to get started with .NET aspire, container apps and IaC.

Details:

I'm currently using azd to deploy my site. I use infra synth with customized bicep files and resource template files. These are generally working quite well.

Editing and testing changes to the project template files is painful. That is, specifically modifications to:
projectname.AppHost/infra/subproject.tmpl.yaml

It is poorly documented, so a lot of edits are 'guess and test', but this edit and test is painfully slow. The lack of documentation is okay - the system is complicated and new technology - but speeding it up will help a lot.

I am finding that that azd deploy actually does two things: (1) first pushes the new container image, then (2) provisions the specific container app resource When debugging my changes to the configuration files, the process of pushing the container image is a time killer.

As an aside, I think clearer documentation around split of provisioning and deployment might be useful. It reads now that these resource templates are provisioned under "azd provision", which is not what I am experiencing.

I would like to be able to deploy/provision changes to the resource template, but use whatever container image is already in the container registry.

It's particularly annoying because simple errors in the template, such as the MI doesn't have permissions to the KeyVault secret, are quick to check but don't occur until after the container image is uploaded.