ci: Use golangci-lint

[abhinav]

Commits are individually reviewable

---

We've been using a hand-rolled lint setup for a while.
It's limiting, and so we've neglected to keep our lints up to date.

This PR switches to using golangci-lint to run linters.
staticcheck is included and enabled by default.
We add revive and a few others.

This also allows the linter to run in parallel with the tests.

See also uber-go/zap#1323 for a similar change to Zap.

Commits after the first one are fixes to the lints found by golangci-lint.
Some of these are:

• Files should be gofumpt-ed.

• Shouldn't add type in var x T = y when type of y is T.

  annotated.go:120:15: var-declaration: should omit type reflect.Type from declaration of var _typeOfError; it will be inferred from the right-hand side (revive)
  annotated.go:645:19: var-declaration: should omit type reflect.Type from declaration of var _typeOfLifecycle; it will be inferred from the right-hand side (revive)
  annotated.go:646:19: var-declaration: should omit type reflect.Type from declaration of var _typeOfContext; it will be inferred from the right-hand side (revive)
  internal/lifecycle/lifecycle.go:198:18: var-declaration: should omit type appState from declaration of var returnState; it will be inferred from the right-hand side (revive)
  

• Should use errors.As and %w when wrapping and unwrapping errors.

  app.go:550:14: type assertion on error will fail on wrapped errors. Use errors.As to check for specific errors (errorlint)
  decorate.go:219:81: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors (errorlint)
  

• All public packages should have doc comments.

• x += 1 should be x++.

  module_test.go:237:5: increment-decrement: should replace p.age += 1 with p.age++ (revive)
  module_test.go:242:6: increment-decrement: should replace p.age += 1 with p.age++ (revive)
  

[JacobOaks]

This seems much cleaner! The exclusions you configured make sense. LGTM.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e7a70af) 98.80% compared to head (2b22135) 98.74%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1150      +/-   ##
==========================================
- Coverage   98.80%   98.74%   -0.07%     
==========================================
  Files          36       30       -6     
  Lines        3106     2950     -156     
==========================================
- Hits         3069     2913     -156     
  Misses         30       30              
  Partials        7        7              

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[r-hang]

Thanks for your contribution!