core/types: Add allocation-free EffectiveGasTipInto method

[SatoshiIsHere]

This PR introduces an allocation-free version of the Transaction.EffectiveGasTip method to improve performance by reducing memory allocations.

Changes

• Added a new EffectiveGasTipInto method that accepts a destination parameter to avoid memory allocations
• Refactored the existing EffectiveGasTip method to use the new allocation-free implementation
• Updated related methods (EffectiveGasTipValue, EffectiveGasTipCmp, EffectiveGasTipIntCmp) to use the allocation-free approach
• Added tests and benchmarks to verify correctness and measure performance improvements

Motivation

In high-transaction-volume environments, the EffectiveGasTip method is called frequently. Reducing memory allocations in this method decreases garbage collection pressure and improves overall system performance.

Benchmark Results

As-Is
BenchmarkEffectiveGasTip/Original-10 42089140 27.45 ns/op 8 B/op 1 allocs/op

To-Be
BenchmarkEffectiveGasTip/IntoMethod-10 72353263 16.73 ns/op 0 B/op 0 allocs/op

Summary of Improvements

• Performance: ~39% faster execution (27.45 ns/op → 16.73 ns/op)
• Memory: Eliminated all allocations (8 B/op → 0 B/op)
• Allocation count: Reduced from 1 to 0 allocations per operation

This optimization follows the same pattern successfully applied to other methods in the codebase, maintaining API compatibility while improving performance.

Safety & Compatibility

This optimization has no side effects or adverse impacts because:

• It maintains functional equivalence as confirmed by comprehensive tests
• It preserves API compatibility with existing callers
• It follows clear memory ownership patterns with the destination parameter
• It maintains thread safety by only modifying the caller-provided destination parameter

This optimization follows the same pattern successfully applied to other methods in the codebase, providing better performance without compromising stability or correctness.