Add goimports

[mikenairn]

Something we added to MGC a while back which i think would be good here Kuadrant/multicluster-gateway-controller#365

Adds new Make targets to sort and group project imports make imports and verify imports are sorted and grouped make verify-imports.

make help | grep imports
  imports          Run openshift goimports against code.
  verify-imports   Verify go imports are sorted and grouped correctly.
  openshift-goimports  Download openshift-goimports locally if necessary

Sorting and grouping based on openshift-goimports defaults, with all kuadrant* modules added as an intermediate so they get grouped nearer the modules imports. Script inspired by KCP and other openshift projects.

From openshift-goimports docs:

Organizes Go imports into the following groups:
  
  standard - Any of the Go standard library packages
  other - Anything not specifically called out in this list
  kubernetes - Anything that starts with k8s.io
  openshift - Anything that starts with github.com/openshift
  intermediates - Optional list of groups
  module - Anything that is part of the current module

Also adds job to CI GH action to execute the verify-imports command on all PRs.

[codecov]

Codecov Report

Merging #415 (d0182ac) into main (133645e) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #415   +/-   ##
=======================================
  Coverage   66.26%   66.26%           
=======================================
  Files          38       38           
  Lines        3901     3901           
=======================================
  Hits         2585     2585           
  Misses       1129     1129           
  Partials      187      187           

Flag	Coverage Δ
unit	60.69% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
api/v1beta1 (u)	∅ <ø> (∅)
pkg/common (u)	78.59% <ø> (ø)
pkg/istio (u)	37.11% <ø> (ø)
pkg/log (u)	31.81% <ø> (ø)
pkg/reconcilers (u)	33.44% <ø> (ø)
pkg/rlptools (u)	56.46% <ø> (ø)
controllers (i)	71.39% <ø> (ø)

Files	Coverage Δ
api/v1beta2/authpolicy_types.go	70.83% <ø> (ø)
api/v1beta2/ratelimitpolicy_types.go	17.24% <ø> (ø)
api/v1beta2/route_selectors.go	100.00% <ø> (ø)
controllers/authpolicy_authconfig.go	66.31% <ø> (ø)
controllers/authpolicy_controller.go	78.66% <ø> (ø)
...ontrollers/authpolicy_istio_authorizationpolicy.go	74.42% <ø> (ø)
controllers/authpolicy_status.go	93.44% <ø> (ø)
controllers/gateway_eventmapper.go	80.95% <ø> (ø)
controllers/gateway_kuadrant_controller.go	79.71% <ø> (ø)
controllers/httproute_eventmapper.go	100.00% <ø> (ø)
... and 19 more

[mikenairn]

CI already has a check using goimports so closing this for now