Generate combined deps-info for all updatable modules.

Introduce a singleton apex rule to merge contents of individual
deps-info results into a single output file.

Bug: 149622332
Test: m
Change-Id: I4ab7e1a3527fead97a81a5a2cb0e1e93a429117c
Merged-In: I4ab7e1a3527fead97a81a5a2cb0e1e93a429117c
Exempt-From-Owner-Approval: cp from aosp
(cherry picked from commit 849f844252872e260a35cf958cb25ab4c5ea3e7f)
diff --git a/android/apex.go b/android/apex.go
index 75be150..30152db 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -425,7 +425,8 @@
 	fullListPath OutputPath
 }
 
-type ApexDepsInfoIntf interface {
+type ApexBundleDepsInfoIntf interface {
+	Updatable() bool
 	FlatListPath() Path
 	FullListPath() Path
 }
@@ -438,8 +439,6 @@
 	return d.fullListPath
 }
 
-var _ ApexDepsInfoIntf = (*ApexBundleDepsInfo)(nil)
-
 // Generate two module out files:
 // 1. FullList with transitive deps and their parents in the dep graph
 // 2. FlatList with a flat list of transitive deps