Allow multiple runner modes in a single codspeed cli run

[GuillaumeLagrange]

Summary

• Consolidate poll_results into upload module: merged the two separate poll_results implementations from cli/exec and cli/run into a single upload::poll_results function driven by PollResultsOptions
• Add local_data to upload metadata: new LocalData struct carrying expected_run_parts_count; local runs now provide a stable run_id and a per-executor run_part_id in the upload metadata
• Introduce Orchestrator for multi-mode execution: new Orchestrator struct owns shared state (provider, system_info, logger) and drives the full lifecycle — setup → run all modes in sequence (each with its own profile folder) → upload all results → poll; mode CLI arg and shell session now accept Vec<RunnerMode> (comma-separated or space-separated)

Test plan

• cargo test passes
• codspeed run --mode simulation cargo bench still works as before
• codspeed run --mode simulation,walltime cargo bench runs both modes and uploads two run parts

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

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_{Comparing cod-1907-multiple-runner-modes-in-a-single-codspeed-cli-run (79ac610) with main (5730358)}