Add `--except` option to `igniter.upgrade`

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

Not related to a problem. It's just a nice-to-have IMO.

### Describe the solution you'd like

I think it would be nice to add an `--except` option to the `igniter.upgrade` mix task so that we can use it together with `--all` to upgrade everything _except_ some packages.

Here's an example:

```bash
mix igniter.upgrade --all --except phoenix_live_view
```

This would upgrade all dependencies in the project, _except_ `phoenix_live_view`.

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start at the `mix igniter.upgrade` mix task and inspect how the existing `--all` option selects packages. Determine where command-line options are parsed and how exclusions should interact with `--all`; done means the example command upgrades every dependency except `phoenix_live_view`, with the relevant test coverage passing.

Written by the indexing model from the issue text.