Feat; Estimated duration for benchmark requests

[Jamesbarford]

Modifies a SQL query to bring back an estimated_completed_at column for in_progress requests.

• Update InProgress enum variant to have an estimated_completed_at field
• Rename update_benchmark_request_status to set_benchmark_request_in_progress and only set the status to in_progress
• Small update to frontend to display the estimated time in bold

[Jamesbarford]

We're preferring a Rust-first solution to estimating times as it will be more maintainable for the codebase & more familiar to people than a moderately arcane SQL query.