`aspire run` arguments are case sensitive

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Describe the bug

In this repo, run the following commands

```bash
aspire run --AppHost playground\stress
aspire run --apphost playground\stress
```

I'd expect them to do the same thing. But the former ignores the `--AppHost` argument and scans the entire repo. It looks like the argument is case sensitive to me.

Sort of related is that I'd expect `aspire run playground\stress to behave the same, but like the first scenario, it starts the app host as if the argument weren't there.

### Expected Behavior

I expect arguments to be case insensitive, or produce an error if invalid arguments are provided.

### Steps To Reproduce

In this repo, compare the following two commands
```bash
aspire run --AppHost playground\stress
aspire run --apphost playground\stress
```

### Exceptions (if any)

_No response_

### Aspire doctor output

_No response_

### Anything else?

_No response_

Start by reproducing the two `aspire run` commands with `--AppHost` and `--apphost`, plus `aspire run playground\stress`, then trace the `aspire run` argument parsing entry point. Done means casing is handled consistently, or invalid arguments produce an error, with tests covering the reported command forms.

Written by the indexing model from the issue text.