add "p.adjust.method" to `stat_compare_means`

[kapsner]

Feature request:

It would be great to have the argument p.adjust.method available when computing comparisons using the function stat_compare_means.

Currently, p-value adjustment is defaulted to "holm" and cannot be accessed directly. Instead, for using different p-value adjustment methods, a workaround is required by using compare_means to create a tibble and provide it to stat_pvalue_manual.

[maltezacharias]

+1, although I believe currently it's hardcoded to none, which disables p adjustment.