Suggestion: add a --sort option to output formats

[kkier]

We currently get a lot of use out of custom formats like format = "{timestamp!d:%b%d %R::>12h} {state:>10} {nnodes:>6} {reason:<80.80+} {nodelist}" and then piping to sort to get chronological order. Piping output isn't exactly a big lift, but a --sort option built into flux would let me define preconfigured formats in the toml files with sorted output, and could be further useful for things like sorting flux jobs by node count.

[chu11]

Related issue #3066