Add "updatable" property to ApexModule interface.

For a given variant of a module that implements ApexModule interface,
the "updatable" property tests if this variant comes from an updatable
apex. For platform variants it is always false.

Test: lunch aosp_walleye-userdebug && m nothing
Bug: 138994281
Change-Id: I2d4c54fb397e29dc9b3203be7fb17be4536529f7

android/apex.go

@@ -32,6 +32,7 @@ type ApexInfo struct {
 	ApexName string
 
 	MinSdkVersion int
+	Updatable     bool
 }
 
 // Extracted from ApexModule to make it easier to define custom subsets of the
@@ -104,6 +105,9 @@ type ApexModule interface {
 	// For example, with maxSdkVersion is 10 and versionList is [9,11]
 	// it returns 9 as string
 	ChooseSdkVersion(versionList []string, maxSdkVersion int) (string, error)
+
+	// Tests if the module comes from an updatable APEX.
+	Updatable() bool
 }
 
 type ApexProperties struct {
@@ -229,6 +233,10 @@ func (m *ApexModuleBase) checkApexAvailableProperty(mctx BaseModuleContext) {
 	}
 }
 
+func (m *ApexModuleBase) Updatable() bool {
+	return m.ApexProperties.Info.Updatable
+}
+
 type byApexName []ApexInfo
 
 func (a byApexName) Len() int           { return len(a) }