* Added peer type resolution for arrays and vectors: the vector type is
selected.
* Fixed passing the lhs type or rhs type instead of the peer resolved
type when calling Value methods during analyzeArithmetic handling of
comptime expressions.
* `checkVectorizableBinaryOperands` now allows mixing vectors and
arrays, as long as one of the operands is a vector.
This matches stage1's handling of `^=` but apparently stage1 is
inconsistent and does not handle e.g. `*=`. stage2 now will always allow
mixing vector and array operands for all operations.
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