[features] Enable plugins and nix install (#383)

## Summary

Turn on the feature flags

## How was it tested?

Author: mikeland73

internal/boxcli/featureflag/feature.go

@@ -14,6 +14,7 @@ type feature struct {
 
 var features = map[string]*feature{}
 
+// nolint:unparam
 func disabled(name string) *feature {
 	if features[name] == nil {
 		features[name] = &feature{name: name}
@@ -22,6 +23,7 @@ func disabled(name string) *feature {
 	return features[name]
 }
 
+// nolint:unparam
 func enabled(name string) *feature {
 	if features[name] == nil {
 		features[name] = &feature{name: name}

internal/boxcli/featureflag/nixinstaller.go

@@ -1,3 +1,3 @@
 package featureflag
 
-var NixInstaller = disabled("NIX_INSTALLER") // DEVBOX_FEATURE_NIX_INSTALLER
+var NixInstaller = enabled("NIX_INSTALLER") // DEVBOX_FEATURE_NIX_INSTALLER

internal/boxcli/featureflag/pkgconfig.go

@@ -1,3 +1,3 @@
 package featureflag
 
-var PKGConfig = disabled("PKG_CONFIG") // DEVBOX_FEATURE_PKG_CONFIG
+var PKGConfig = enabled("PKG_CONFIG") // DEVBOX_FEATURE_PKG_CONFIG