gh-35362: Implement infinite sums and products for lazy series
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We allow lazy series to compute infinite sums `\sum_{i \in I} p_i` and
products `\prod_{i \in I} (1 + p_i)` over arbitrary (enumerated) index
sets `I` subject to a somewhat mild technical constraint that the order
of each input `p_i` is weakly increasing wrt the iteration order and the
preimage of each order is finite.
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### :hourglass: Dependencies
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- #35265
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URL: https://github.com/sagemath/sage/pull/35362
Reported by: Travis Scrimshaw
Reviewer(s): Martin Rubey, Travis Scrimshaw
