Enable nolintlint linter

[jeanduplessis]

There currently exists a pattern of //nolint directives disabling linters without saying why.
We should enable the nolintlint linter, that'll require explanatory comments for //nolint directives.
This helps the reader understand why a //nolint directive was appropriate.
As a bonus, it'll also automatically remove //nolint directives that don't do anything anymore.

[negz]

I think it'd be a good idea to take the linter configuration from c/c and replicate it here.

A while back we changed c/c to "opt-in" for all linters rather than opt out. The migration is a bit toilsome due to all the newly enabled linters but I feel it's a good thing overall. While working in this repo for the last few days I've certainly seen a lot of little cases where I've thought "I wish a linter caught that".