Localize helm fields (#4978)

* Localize helm fields

* Address readability feedback

* Handle edge cases

* Improve readability

Split copyChartHome and use existence to prevent repeated copying.

plugin/builtin/helmchartinflationgenerator/HelmChartInflationGenerator.go

@@ -89,7 +89,7 @@ func (p *plugin) validateArgs() (err error) {
 	// the loader root (unless root restrictions are
 	// disabled, in which case this can be an absolute path).
 	if p.ChartHome == "" {
-		p.ChartHome = "charts"
+		p.ChartHome = types.HelmDefaultHome
 	}
 
 	// The ValuesFile may be consulted by the plugin, so it must