[Automation] Allow "Project selection" to be set as "Choose at runtime"

### Feature summary

Allow a single automation to be used across multiple projects

### What problem are you trying to solve?

I have a workflow of updating a nuget package across a dozen repositories, being able to have a single automation and on running it choosing the project would allow be to avoid having a dozen identical automations each with their own project.

### Proposed solution

Have an experience for project to be selected when running it.

### Workflow impact

Allows reuse of an automation in multiple projects

### Installation context

_No response_

### Additional context

_No response_

No files, tests, or entry points are named in the issue. Start by locating the automation run flow and the current project-selection configuration, then determine how a project can be chosen at runtime. Done means one automation can be reused across multiple repositories with the project selected when it runs.

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