Deprecate/remove interfacer from supported linters

[dackroyd]

mvdan/interfacer@c200402

Deprecated: A tool that suggests interfaces is prone to bad suggestions, so its usefulness in real code is limited. This tool will remain available as a proof of concept, and for others to examine and learn from.

[jirfag]

Hi,

1. we can't do it before v2.0.0
2. I'm not sure we should do it because some users may find it useful.
3. but we can disable it from default set of linters

[andig]

I second this. Interfacer produces false positives, too.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[pkuca]

Interfacer is used to create a fair comparison with gometalinter in the benchmarks - how should that be handled?

#1689 is a dupe

[ldez]

gometalinter is now archived so a fair comparison with a dead project seems impossible.
https://github.com/alecthomas/gometalinter#go-meta-linter

[pkuca]

Agreed - knowing that, I can take this unless @sayboras has stuff in progress I see it's queued up for v2, so nevermind.