Move model crate stubs into defaults

[fhill2]

Pull Request

If a rust project depends on nautilus_model crate, the project only compiles by including the "stubs" feature.

This is due to the Default trait impls being included in the production execution path, while also being gated behind the "stubs" feature.

The minimal repro for this is building a rust project with the nautilus-model crate as a single dependency.

I've provided a fix that moves the trait impls into either of these locations:

• <module_name>/default.rs -> any code used in production for derive(Default) unwrap_or_default()
• <module_name>/stubs.rs -> anything used in the test execution path

Type of change

Delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How has this change been tested?

Test 1:

cargo build in a rust Project that depends on crate nautilus_model compiles successfully with no additional features.

nautilus-model = { path = "./nautilus_trader/nautilus_core/model"}

Test 2:

make install-debug builds successfully.

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All committers have signed the CLA.

[cjdsellers]

Hi @fhill2

Good to hear for you. Thanks for the contribution, I think this partitioning is much cleaner 👍
I'll do another pass of the stubs feature as well.