Could `pal_seq_gradient` and `pal_div_gradient` be renamed to `pal_gradient_*`?

[davidhodge931]

It'd be easier if these were a family of functions with a consistent prefix pal_gradient.

Thought maybe could be something for tidyverse dev day?

Appreciate all this naming and renaming is a bit of a pain, but I think consistent prefixes help organise everything in one's brain

Current

pal_gradient_n()
pal_seq_gradient()
pal_div_gradient()

Desired

pal_gradient_n()
pal_gradient_seq()
pal_gradient_div()