engineering: Add parsing support for COSI 1.2

[frhuelsz]

🔍 Description

Adds deserialization and validation with testing for COSI 1.2.

[Copilot]

Pull request overview

This PR adds parsing and validation support for COSI (Composable OS Image) specification version 1.2, which introduces partition metadata to track original partition information alongside filesystem images.

Changes:

• Adds KnownMetadataVersion::V1_2 enum variant and corresponding version handling
• Introduces Partition struct to represent partition metadata with fields for path, size, type, UUID, label, and number
• Adds partitions optional field to CosiMetadata and image_files() helper method
• Implements v1.2 validation rules for partition metadata including uniqueness checks and path validation
• Adds comprehensive error types for v1.2 validation failures
• Updates documentation table formatting for improved readability

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/Reference/Composable-OS-Image.md	Formatting improvements to Partition object table for better readability
crates/trident/src/osimage/cosi/metadata.rs	Adds V1_2 version variant, Partition struct definition, partitions field, and image_files() iterator method
crates/trident/src/osimage/cosi/validation.rs	Implements v1.2 validation logic for partitions with tests covering duplicate numbers, zero numbers, unknown paths, and missing partitions
crates/trident/src/osimage/cosi/error.rs	Adds four new error variants for v1.2 partition validation failures
crates/trident/src/osimage/cosi/mod.rs	Updates test fixtures to include partitions field for existing v1.0 metadata