Add chassismanager package.

[Chounoki]

No description provided.

[gemini-code-assist]

Code Review

This pull request introduces an in-memory chassis manager implementation for the Bootz server, including its Bazel build configuration. The implementation provides functionality to resolve chassis metadata, generate bootstrap data, and track device status updates. Feedback from the review highlights the need to include the ServerTrustCert in the bootstrap response for secure boot validation, optimize chassis lookups by using a map instead of a slice for better performance, and ensure all relevant fields are populated during chassis resolution.