Gofumpt lints more tightly than gofmt + goimports, and produces more regular code.

Today I saw @mholt's tweet about a feature freeze, and wanting to improve quality. When faced with such situations and a go codebase, I typically break out golangci-lint. So, here's the PR's:

• chore: use gofumpt #5707
• chore: use gci linter #5708
• chore: Lint tests #5709
• chore: use revive linter #5712

They build off of one another, beginning with gofumpt. The one that lints the tests will be the most involved.

Goal

So, the goal of this would be to find small bugs/errors or put tests in more places, while creating a strict format for the code that coders don't need to enfoirce.

I can't say for sure that I can accomplish any style desire, but after a few years of doing extensive bughunting with golangci-lint and other tools, I can say that I can probably accomplish almost any style desire.