bug#30757: Better manipulation (suppressing, examining type) of warnings from *Warnings* buffer

[Drew Adams]

> It would be nice if warnings in the *Warnings* buffer came with some
> kind of button to let the user add the relevant value to
> warning-suppress-types or warning-suppress-log-types.

+1

It would be good for the button/link to open *Help* with a more
complete description of the warning.  And there (in *Help*) there
could be buttons/links to suppress things.

In addition, we might have a command or commands that would
show such *Help* regardless of whether the warnings are being
shown.  In *Help*, if the warning is currently not being
shown then the button/link would enable showing it (i.e.,
the button toggles the behavior show/suppress).