Adds On-demand scope API for active scanning

[sebdraven]

Adds support for ONYPHE's On-demand scope API, letting users actively scan an IP, CIDR or domain (single or bulk) instead of only reading previously collected data.

• Adds ondemand_scope_ip, ondemand_scope_domain, ondemand_scope_ip_bulk, ondemand_scope_domain_bulk and ondemand_scope_result to both Onyphe and AsyncOnyphe, sharing optional import_results, vulnscan, urlscan, ports and maxscantime tuning
• Marks the bulk endpoints as living under ONYPHE's unstable /dev/ prefix, and the domain single endpoint as an undocumented, by-analogy path, each isolated behind a single constant so a future fix is a one-line change
• Prevents accidental double scans: send() gains a retry: bool flag so launches (POST) are never retried on 429/5xx/transport errors, while result retrieval (GET) keeps the usual retry behaviour
• Introduces ScanInProgressError (subclassing APIError, carrying .scan_id) to distinguish a still-running scan (ONYPHE codes 103/111) from an actual failure, regardless of the HTTP status carrying it
• Adds pyonyphe ondemand ip|domain|ip-bulk|domain-bulk|result CLI commands, with bulk commands reading targets from a file and ondemand result exiting with code 3 while the scan is still in progress
• Documents the new API and exception across the README, CLI, API and usage docs, and adds test coverage for specs, both clients and the CLI