rust modules can be included in apex

We will have some APEXes having rust binaries and libraries. So, adding
the support for the types of modules.

rust.Module now inherits from android.ApexModuleBase and implements
the android.ApexModule interface.

Bug: 172414324
Test: m

Exempt-From-Owner-Approval: rebased after +2 from the owner
Change-Id: I356ef4c45f782a6460f001e83af96d1710642d80

rust/rust_test.go

@@ -120,6 +120,7 @@ func (tctx *testRustCtx) useMockedFs() {
 // attributes of the testRustCtx.
 func (tctx *testRustCtx) generateConfig() {
 	tctx.bp = tctx.bp + GatherRequiredDepsForTest()
+	tctx.bp = tctx.bp + cc.GatherRequiredDepsForTest(android.NoOsType)
 	cc.GatherRequiredFilesForTest(tctx.fs)
 	config := android.TestArchConfig(buildDir, tctx.env, tctx.bp, tctx.fs)
 	tctx.config = &config