[llvm] [AArch64][NEON] Fold insert(zero, extract(X, 0), 0) -> X when X is known to zero lanes 1-N (PR #213940)

[Kerry McLaughlin via llvm-commits]

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kmclaughlin-arm wrote:

The opcodes are being added to `isLanes1toNKnownZero` without checking for any particular type, so maybe it's enough to add one test for each?

https://github.com/llvm/llvm-project/pull/213940