RFC: Make isapprox compare element-wise when the vector norm is infinite (#17658)
* Make isapprox compare elementwise when the vector norm is infinite
* Test change to isapprox for arrays
* Documented isapprox fallback behavior
* Document change to isapprox fallback when norm(x,y) is infinite
* Put docs in the right place hopefully
* Commit the auto-generated change
* Remove use of map, reword explanation of behavior