feat(rm): add EXT-INT64 support

Add INT64 data type support across all applicable TOSA operations in the reference model, enabling 64-bit integer computation.

• Operators updated with INT64 support:
  • Element-wise Binary: ADD, SUB, MUL, INTDIV, MAXIMUM, MINIMUM, POW, ARITHMETIC_RIGHT_SHIFT, LOGICAL_LEFT_SHIFT, LOGICAL_RIGHT_SHIFT, BITWISE_AND, BITWISE_OR, BITWISE_XOR
  • Element-wise Unary: ABS, BITWISE_NOT, CLZ, NEGATE
  • Comparison: EQUAL, GREATER, GREATER_EQUAL
  • Ternary: SELECT
  • Reduction: REDUCE_MAX, REDUCE_MIN, REDUCE_SUM
  • Tensor: ARGMAX
  • Data Layout: CONCAT, PAD, RESHAPE, REVERSE, SLICE, TILE, TRANSPOSE
  • Scatter/Gather: GATHER, SCATTER
  • Type Conversion: CAST, IDENTITY
• Add overflow protection for INT64 edge cases
• Improve INT64 unittest coverage