Make default boot state user configurable

[ayodejiige]

This pull request introduces a new BootStatePolicy trait to the bootloader library, allowing bootloader applications to do the following:

1. Set a default boot state specific to their application
2. Perform application specific validation on the current boot state. A valid boot state from the perspective of the slimloader library may not be valid for the application. For example, up to 7 slots are possible but a specific application may have only 2.

The trait is defined for the Config structure and not the Board structure since this policies are application specific and not platform dependent.

[Copilot]

Pull Request Overview

This PR introduces a configurable default boot state mechanism, allowing users to customize the initial state when no state is loaded from the journal. The change replaces the hardcoded default boot state with a trait-based approach.

• Introduces a DefaultBootState trait with a customizable default_state() method
• Updates the Board trait to require Config types to implement DefaultBootState
• Refactors the boot initialization logic to use the trait-provided default state

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
libs/ec-slimloader/src/lib.rs	Defines the DefaultBootState trait and updates Board::Config to require it; refactors boot state initialization to use the trait method
libs/ec-slimloader-imxrt/src/lib.rs	Adds DefaultBootState trait bound to the Board implementation for IMXRT platforms
examples/rt685s/bootloader/src/main.rs	Implements DefaultBootState for the example configuration using default trait implementation

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[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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[Wassasin]

/approve