bug#52383: 29.0.50; [suggestion] Add seq-set-subset-p to seq.el

[Juri Linkov]

> BTW function `seq-set-equal-p' could be rewritten using
> `seq-set-subset-p'.

Isn't the word "set" redundant in the name?
In `seq-set-equal-p' the word "set" is needed
to say "is set equal".  But in `seq-set-subset-p'
the word "set" doesn't add much meaning, so better
would be to name your new function just `seq-subset-p'.