Comprehensive test suite for SCPI command parsing:
- SCPICommand dataclass tests (creation, keyword property)
- Parser tests for queries, commands, arguments
- IEEE 488.2 common command tests (*IDN?, *RST, etc.)
- Edge cases (whitespace, empty strings)
- Instrument-specific command tests
Also fixed bug where is_query was determined from command string
ending rather than header ending (handles queries with arguments).
Adds SCPIParser class with parse() method that handles:
- IEEE 488.2 common commands (*IDN?, *RST, etc.)
- Query commands (ending with '?')
- Commands with comma-separated arguments
- Whitespace stripping