Pin pedantic lints to 1.8.0

[kwalrath]

Related discussion: dart-lang/site-www#1016 (comment)

[kevmoo]

At a minimum, I think updating the templates to drop them is great.

Not 100% sure about enabling the lints for end users, though...

[kwalrath]

1.8.0 pedantic includes unnecessary_new & unnecessary_const, as does the stagehand options file. When we update stagehand (and its templates) to pedantic 1.8.0, we should remove duplicate declarations (such as unnecessary_new & unnecessary_const) from the the stagehand options file.

[kwalrath]

We should avoid having a free-floating pedantic dependency, since that's likely to break code whenever devs do a pub upgrade.

If we continue to use pedantic, we should have something like this in each template's analysis_options.yaml file:

include: package:pedantic/analysis_options.1.9.0.yaml

Currently, the analysis options files have something like this (which I'm calling a free-floating pedantic dependency):

include: package:pedantic/analysis_options.yaml

[kwalrath]

/cc @mit-mit

[mit-mit]

I'd recommend pinning to pedantic 1.8.0 for now. We're investigating using a different default set of lints, so no reason to push additional lints right now.