Rename apexDepsMutator to apexInfoMutator

Generally ...DepsMutator methods add dependencies between modules but
the apexDepsMutator does not which can be confusing. This renames
apexDepsMutator to apexInfoMutator and adds some extra documentation to
clarify its function. It also renames the registered name for the
mutator and its associated providers from apex_deps to apex_info.

Test: m nothing
Bug: 171061220
Change-Id: Ic074a281215b23e982448ccff7ac075236123bee
diff --git a/android/apex.go b/android/apex.go
index a4ff0f9..4a71b40 100644
--- a/android/apex.go
+++ b/android/apex.go
@@ -257,7 +257,7 @@
 	canHaveApexVariants bool
 
 	apexInfos     []ApexInfo
-	apexInfosLock sync.Mutex // protects apexInfos during parallel apexDepsMutator
+	apexInfosLock sync.Mutex // protects apexInfos during parallel apexInfoMutator
 }
 
 // Initializes ApexModuleBase struct. Not calling this (even when inheriting from ApexModuleBase)
@@ -442,7 +442,7 @@
 	} else {
 		apexInfos = base.apexInfos
 	}
-	// base.apexInfos is only needed to propagate the list of apexes from apexDepsMutator to
+	// base.apexInfos is only needed to propagate the list of apexes from apexInfoMutator to
 	// apexMutator. It is no longer accurate after mergeApexVariations, and won't be copied to
 	// all but the first created variant. Clear it so it doesn't accidentally get used later.
 	base.apexInfos = nil