Allow setting multiple parameters at once at runtime

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

docker-compose has docker-compose.override.yml.

AppSettings.json can have environment-specific override files.

Aspire allows leaving parameters unset in configuration files, and will then prompt for them via the dashboard **one by one**.

This request is to allow setting multiple parameters at once via the dashboard.

### Describe the solution you'd like

Ideas could be e.g. by uploading a json/yaml file, or by pasting that in a dialog upon first run.

### Additional context

_No response_

Start with the Aspire dashboard flow that prompts for unset parameters, then trace how runtime parameter values are collected and applied. The feature should support supplying multiple parameters together, such as through a JSON/YAML upload or a pasted configuration, rather than prompting one by one.

Written by the indexing model from the issue text.