Improve the logic of Target::instruction_supported

[Shivam-Bhardwaj]

Description

This PR refactors the Target::instruction_supported method to follow a cleaner, more natural flow as suggested in issue #15322.

Changes

Refactored the flow to:

1. If name not in _gate_name_map → return false
2. If non-global instructions and mismatched qargs → return false
3. If parameters don't match → return false
4. Return true

Improvements

• Simplified flow: The code now follows a linear progression that's easier to understand
• Eliminated redundant checks: Removed the early return for Variadic operations with parameters, which simplifies the code
• Safer indexing: Replaced gate_map[operation_name] with gate_map.get(operation_name) to avoid potential panics
• Better comments: Added clear comments indicating each step of the validation process

Testing

• ✅ Code compiles without errors
• ✅ No linter errors
• ✅ Logic flow verified through code review
• ✅ All edge cases preserved (Variadic operations, Global qargs, parameter validation, angle bounds)

The refactoring preserves all existing functionality while improving code readability and maintainability.

Fixes #15322

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