Enable fieldalignment linter, then ignore it

This enables the fieldalignment linter by enabling all `govet` checks
except shadowing. I then configured it to ignore large swaths of code
(tests, cmd/, APIs), and nolint'd all the existing complaints because
they seemed irrelevant.

Also removed existing nolint:maligned, as the linter is off.

Closes #2325

.golangci.yml

@@ -66,6 +66,12 @@ linters:
     - unparam
 
 linters-settings:
+  govet:
+    disable-all: false
+    enable-all: true
+    disable:
+      # extremely noisy, also against common Go style in most cases
+      - shadow
   gocritic:
     enabled-tags:
       - performance
@@ -90,3 +96,11 @@ issues:
   exclude-use-default: false
   exclude:
     - Using the variable on range scope .* in function literal
+  exclude-rules:
+    # Skip fieldalignment checks on:
+    # - tests: memory footprint doesn't matter
+    # - cmd/: we assume these are one-off config entries
+    # - pkg/apis: Keep strong convention on TypeMeta/ObjectMeta/Spec/Status
+    - path: '(.+)_test\.go|^test/|^cmd/.*|^pkg/apis/.*'
+      # fieldalignment is in the `govet` linter, so exclude based on text instead of all of govet
+      text: '^fieldalignment: .*'

pkg/cloudproduct/gke/gke.go

@@ -37,6 +37,8 @@ var logger = runtime.NewLoggerWithSource("gke")
 type gkeAutopilot struct{}
 
 // hostPortAssignment is the JSON structure of the `host-port-assignment` annotation
+//
+//nolint:govet // API-like, keep consistent
 type hostPortAssignment struct {
 	Min           int32           `json:"min,omitempty"`
 	Max           int32           `json:"max,omitempty"`

pkg/fleetautoscalers/controller.go

@@ -58,12 +58,16 @@ import (
 )
 
 // fasThread is used for tracking each Fleet's autoscaling jobs
+//
+//nolint:govet // ignore fieldalignment, low count
 type fasThread struct {
 	generation int64
 	cancel     context.CancelFunc
 }
 
 // Controller is the FleetAutoscaler controller
+//
+//nolint:govet // ignore fieldalignment, singleton
 type Controller struct {
 	baseLogger            *logrus.Entry
 	clock                 clock.Clock

pkg/gameserverallocations/cache.go

@@ -21,6 +21,8 @@ import (
 )
 
 // gameserver cache to keep the Ready state gameserver.
+//
+//nolint:govet // ignore fieldalignment, low count
 type gameServerCacheEntry struct {
 	mu    sync.RWMutex
 	cache map[string]*agonesv1.GameServer

pkg/gameservers/controller.go

@@ -63,6 +63,8 @@ const (
 )
 
 // Controller is a the main GameServer crd controller
+//
+//nolint:govet // ignore fieldalignment, singleton
 type Controller struct {
 	baseLogger             *logrus.Entry
 	sidecarImage           string

pkg/gameservers/pernodecounter.go

@@ -34,6 +34,8 @@ import (
 // Ready GameServers currently exist on each node.
 // This is useful for scheduling allocations, fleet management
 // mostly under a Packed strategy
+//
+//nolint:govet // ignore fieldalignment, singleton
 type PerNodeCounter struct {
 	logger           *logrus.Entry
 	gameServerSynced cache.InformerSynced

pkg/gameservers/portallocator.go

@@ -41,6 +41,8 @@ type portAllocation map[int32]bool
 // appropriate locking is taken.
 // The PortAllocator does not currently support mixing static portAllocations (or any pods with defined HostPort)
 // within the dynamic port range other than the ones it coordinates.
+//
+//nolint:govet // ignore fieldalignment, singleton
 type PortAllocator struct {
 	logger             *logrus.Entry
 	mutex              sync.RWMutex

pkg/gameserversets/gameserver_state_cache.go

@@ -22,6 +22,8 @@ import (
 )
 
 // gameServerSetCacheEntry manages a list of items created and deleted locally for a single game server set.
+//
+//nolint:govet // ignore fieldalignment, not many
 type gameServerSetCacheEntry struct {
 	mu              sync.Mutex
 	pendingCreation map[string]*agonesv1.GameServer

pkg/metrics/controller.go

@@ -68,6 +68,8 @@ func init() {
 }
 
 // Controller is a metrics controller collecting Agones state metrics
+//
+//nolint:govet // ignore fieldalignment, singleton
 type Controller struct {
 	logger                    *logrus.Entry
 	gameServerLister          listerv1.GameServerLister

pkg/sdkserver/localsdk.go

@@ -73,6 +73,8 @@ func defaultGs() *sdk.GameServer {
 // LocalSDKServer type is the SDKServer implementation for when the sidecar
 // is being run for local development, and doesn't connect to the
 // Kubernetes cluster
+//
+//nolint:govet // ignore fieldalignment, singleton
 type LocalSDKServer struct {
 	gsMutex           sync.RWMutex
 	gs                *sdk.GameServer

pkg/sdkserver/localsdk_test.go

@@ -429,7 +429,6 @@ func TestLocalSDKServerPlayerConnectAndDisconnect(t *testing.T) {
 
 	e := &alpha.Empty{}
 
-	// nolint: maligned
 	fixtures := map[string]struct {
 		testMode bool
 		gs       *agonesv1.GameServer

pkg/sdkserver/sdkserver.go

@@ -71,7 +71,8 @@ var (
 
 // SDKServer is a gRPC server, that is meant to be a sidecar
 // for a GameServer that will update the game server status on SDK requests
-// nolint: maligned
+//
+//nolint:govet // ignore fieldalignment, singleton
 type SDKServer struct {
 	logger             *logrus.Entry
 	gameServerName     string

pkg/util/workerqueue/workerqueue.go

@@ -70,6 +70,8 @@ type Handler func(context.Context, string) error
 // WorkerQueue is an opinionated queue + worker for use
 // with controllers and related and processing Kubernetes watched
 // events and synchronising resources
+//
+//nolint:govet // ignore fieldalignment, singleton
 type WorkerQueue struct {
 	logger  *logrus.Entry
 	keyName string