Add the Variable struct

Adding a struct to represent the variable block in the terraform files
This will help in storing this values while parsing tf files.

module/meta.go

@@ -2,7 +2,7 @@ package module
 
 import (
 	"github.com/hashicorp/go-version"
-	"github.com/hashicorp/terraform-registry-address"
+	tfaddr "github.com/hashicorp/terraform-registry-address"
 )
 
 type Meta struct {
@@ -11,6 +11,7 @@ type Meta struct {
 	ProviderReferences   map[ProviderRef]tfaddr.Provider
 	ProviderRequirements map[tfaddr.Provider]version.Constraints
 	CoreRequirements     version.Constraints
+	Variables            map[string]Variable
 }
 
 type ProviderRef struct {

module/variable.go

@@ -0,0 +1,17 @@
+package module
+
+import (
+	"github.com/hashicorp/hcl-lang/schema"
+	"github.com/zclconf/go-cty/cty"
+)
+
+type Variable struct {
+	Description     string
+	Type            cty.Type
+	TypeConstraints schema.ExprConstraints
+	DefaultValue    cty.Value
+
+	// In case the version it is before 0.14 sensitive will always be false
+	// that was actually the default value for prior versions
+	IsSensitive bool
+}