Add debug ramdisk variant.

A module will be installed to /debug_ramdisk if debug_ramdisk is set to
true.

This is a reland of f84e9c05e2103149162e4a78a68f20c164fbbba2, with a fix
that removes /first_stage_ramdisk.

Bug: 184004542
Test: soong test
Change-Id: I739de63cfec6b0fec5a90f7c4741fc4d884d209c
diff --git a/android/paths_test.go b/android/paths_test.go
index 6ec75b4..f8ccc77 100644
--- a/android/paths_test.go
+++ b/android/paths_test.go
@@ -395,6 +395,19 @@
 			partitionDir: "target/product/test_device/vendor_ramdisk",
 		},
 		{
+			name: "debug_ramdisk binary",
+			ctx: &testModuleInstallPathContext{
+				baseModuleContext: baseModuleContext{
+					os:     deviceTarget.Os,
+					target: deviceTarget,
+				},
+				inDebugRamdisk: true,
+			},
+			in:           []string{"my_test"},
+			out:          "target/product/test_device/debug_ramdisk/my_test",
+			partitionDir: "target/product/test_device/debug_ramdisk",
+		},
+		{
 			name: "system native test binary",
 			ctx: &testModuleInstallPathContext{
 				baseModuleContext: baseModuleContext{