Reland: Get the dex2oat host tool path from module dependency on the

binary module.

This uses the Once cache for GlobalSoongConfig to propagate the dex2oat
path from a module dependency to the singletons (both the one that
writes out dexpreopt_soong.config and the one that creates the
dexpreopted boot images). Unless dexpreopting is disabled altogether
through DisablePreopt in dexpreopt.config, that means:

- We must ensure at least one module registers a dex2oat tool
  dependency and resolves a GlobalSoongConfig using it, or else the
  singletons fail. That means we litter dex2oat dependencies in java
  modules even when they won't get dexpreopted and hence don't really
  need them.

- We still assume there's at least one java_library or android_app in
  the build.

This relands https://r.android.com/1205730 without changes - the
necessary fixes are in the child CLs.

Bug: 145934348
Test: m
  (check that out/soong/dexpreopt_soong.config points to dex2oatd64)
Test: env USE_DEX2OAT_DEBUG=false m
  (check that out/soong/dexpreopt_soong.config points to dex2oat64)
Test: env OUT_DIR=out-tools prebuilts/build-tools/build-prebuilts.sh
  on the aosp-build-tools branch
Change-Id: I66661711b317d1e4ec434861982919bdde19b575

java/app.go

@@ -27,6 +27,7 @@ import (
 
 	"android/soong/android"
 	"android/soong/cc"
+	"android/soong/dexpreopt"
 	"android/soong/tradefed"
 )
 
@@ -875,6 +876,7 @@ type AndroidAppImport struct {
 	android.ModuleBase
 	android.DefaultableModuleBase
 	prebuilt android.Prebuilt
+	dexpreopt.DexPreoptModule
 
 	properties   AndroidAppImportProperties
 	dpiVariants  interface{}