closes #2927

Scripts

This adds the four scripts proposed in #2927.

The scripts all follow the basic pattern of iterating over the go modules in the repo and running the appropriate commands in each directory. Because of this, there is some duplicate code. I chose to keep it this way because deduping it added complexity, and I wanted to keep these scripts as simple as possible to understand.

The only dependencies for these scripts are git and a posix shell.

• script/fmt.sh is the simplest one. It runs go fmt ./... in each module directory.

• script/generate.sh runs go generate ./... and go mod tidy -compat '1.17' in each module directory. It also has a --check flag which causes it to run on a temporary git worktree and fail if any new diff is created.

• script/lint.sh runs golangci-lint run on each module then runs script/generate.sh --check. It installs golangci-lint in bin/ if needed.

• script/test.sh runs go test in each module directory. If arguments are provided, those are used as arguments for go test, otherwise it uses the default arguments -race -covermode atomic ./...

script/lint.sh and script/test.sh skip the module in example/newreposecretwithlibsodium because it cannot compile unless libsodium is available.

CONTRIBUTING.md

• Updates CONTRIBUTING.md to include the new scripts and generally updates the "Submitting a patch" section.

Workflow changes

linter.yml

• Runs script/lint.sh instead of using the golangci-lint action.
• No longer uses a run matrix. Because script/lint.sh iterates over modules, I was able to remove the run matrix. We now only run one lint job instead of four.
• Stale generated files will now be reported on lint runs because script/lint.sh validates go generate.

tests.yml

• Runs script/test.sh instead of running go test multiple times in separate steps.
• No longer checks go generate now that it is checked in lint.
• Only sets -coverprofile when codecov will be updated because -coverprofile prevents cached test results from being used.
• Sets default shell to bash so that it doesn't need to be specified on each step.

Misc changes

Running script/test.sh exposed an issue where the examples module won't compile on Windows because syscall.Stdin is typed differently on Windows. I resolved this by replacing syscall.Stdin with int(os.Stdin.Fd())