Add `kernel_parameter_order` optional field to `BootSettingsV1`

## Background

Related to [bottlerocket-os/bottlerocket#3647](https://github.com/bottlerocket-os/bottlerocket/issues/3647).

Kernel command line argument order can matter (e.g. `hugepagesz` must precede `hugepages`), but `kernel_parameters` is a `HashMap` and the datastore loses ordering through filesystem storage, so there's no way to guarantee output order today.

## Proposed Solution

Rather than changing the datastore to preserve map ordering, I'd like to propose adding an optional field to `BootSettingsV1`:

```rust
kernel_parameter_order: Option>,
```

`prairiedog` would use this to output parameters in the specified order first, then append the rest. If absent, behavior is unchanged.

```toml
[settings.boot]
kernel-parameter-order = ["hugepagesz", "hugepages"]

[settings.boot.kernel-parameters]
hugepagesz = ["1G"]
hugepages = ["4"]
```

For more details on the investigation and proposed approach, see [my comment on the original issue](https://github.com/bottlerocket-os/bottlerocket/issues/3647#issuecomment-3963288161).

Once this field is available, I'll submit PRs for the prairiedog logic in `bottlerocket-core-kit` and the version bump in `bottlerocket`.

Start by locating the BootSettingsV1 definition and its serialization or settings-schema entry points in this Rust SDK. Trace how the optional field would be represented, then verify that the documented settings.boot TOML shape maps to it; done means the field is available without changing behavior when absent.

Written by the indexing model from the issue text.