Refactor IntrinsicFunction handling to align with stable-mir-json and existing development patterns

[Stevengre]

The current implementation of IntrinsicFunction in mono.md deviates from our established patterns for modeling JSON contents in K sorts. This issue tracks the technical debt introduced in PR #659 to enable intrinsic function support, which we're accepting temporarily to unblock development.

Current Issues

1. Inconsistent Symbol Naming Convention
   - The IntrinsicFunction constructor lacks the MonoItemKind:: prefix that other constructors use
   - Current: IntrinsicFunction(Symbol)
   - Expected: MonoItemKind::IntrinsicFunction(Symbol) or similar
2. Deviation from JSON Modeling Pattern
   - Previously, all sorts used by kmir-ast.md were directly present in the JSON
   - IntrinsicFunction introduces a K-specific constructor that doesn't directly correspond to the JSON structure
   - This breaks the 1:1 mapping between stable-mir-json output and K sorts

Proposed Solution

Consider refactoring to use a different sort structure that better separates concerns:

• Create distinct constructors like Function(Symbol, Body) and Intrinsic(Symbol) in the runtime function table. This would maintain the JSON modeling integrity while still supporting intrinsic functions
• Don't tightly couple stable-mir-json and kmir, but rather let stable-mir-json focus on extracting all useful MIR information, while kmir focuses on formal semantics. The connection between stable-mir-json and kmir can also be accomplished through a tool.

Context

• Related PR: Implement std::hint::black_box intrinsic support in KMIR #659 (initial intrinsic function support)
• Related stable-mir-json PR: Use mangled name for intrinsic symbols stable-mir-json#85
• Affected files:
  • kmir/src/kmir/kdist/mir-semantics/mono.md:37
  • kmir/src/kmir/kmir.py (function map generation)
  • kmir/src/kmir/kdist/mir-semantics/kmir.md (intrinsic execution rules)

Notes

This refactoring should be done after:

1. The relationship between kmir and stable-mir-json is better defined
2. Any broader kmir refactoring efforts are completed
3. The stable-mir-json intrinsics PR is merged and stabilized