Support user specifying syft-json version

Like we've done with other formats, we'd like to be able to have the user be able to select the syft-json version on the CLI:

```
syft myimage:latest -o json@16
```

This way we can add new schemas with breaking changes that are opt in, not the default, thus allows us to iterate on core format models without forcing a syft v2 build:

```
syft myimage:latest -o json@17-dev
```

Start by inspecting how existing output formats accept user-selected versions on the CLI, then trace the corresponding format and schema selection paths. Run the CLI with the examples in this issue and verify that json@16 and json@17-dev select the requested schemas while the default remains unchanged.

Written by the indexing model from the issue text.