Add missing fixed-sized primops and constant folding

Part of the work towards #19026 (closed).

• inversePrimOp is renamed to semiInversePrimOp to indicate the given primop is only a right inverse, not left inverse (and contra-wise for the primop which we are giving rules for). This explains why are new usage is not incorrect.

• The removed subsumedByPrimOp calls were actually dead as the match on ill-typed code. @hsyl20 pointed this out in !4390 (closed) (comment 311912),

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