Preserve Enumerable.SequenceEqual binding for arrays

Make originally resolved reduced Enumerable.SequenceEqual calls with two array operands explicit before retargeting. Preserve LINQ null-operand exceptions and method identity when newer span binding would treat null arrays as empty spans. Evaluate operands once in their original order. Retain strings, nonarray operands, explicit generic arguments, comparer overloads, custom/static calls, comments and conditional snapshots.