Update min_sdk_version from SdkSpec to ApiLevel

This relands aosp/2457063. The original change broke T and U since those
branches still contain soong modules of type (kind+level). Those soong
modules have been cleaned up now

Test: Used go/abtd to test T and U branches with this change

Bug: 208456999
Change-Id: I0ef7933c055f88cb512a02108f1173e51156ef1c
diff --git a/android/sdk_version.go b/android/sdk_version.go
index ab6e4f7..2107cbe 100644
--- a/android/sdk_version.go
+++ b/android/sdk_version.go
@@ -25,9 +25,9 @@
 	SdkVersion(ctx EarlyModuleContext) SdkSpec
 	// SystemModules returns the system_modules property of the current module, or an empty string if it is not set.
 	SystemModules() string
-	// MinSdkVersion returns SdkSpec that corresponds to the min_sdk_version property of the current module,
+	// MinSdkVersion returns ApiLevel that corresponds to the min_sdk_version property of the current module,
 	// or from sdk_version if it is not set.
-	MinSdkVersion(ctx EarlyModuleContext) SdkSpec
+	MinSdkVersion(ctx EarlyModuleContext) ApiLevel
 	// ReplaceMaxSdkVersionPlaceholder returns SdkSpec to replace the maxSdkVersion property of permission and
 	// uses-permission tags if it is set.
 	ReplaceMaxSdkVersionPlaceholder(ctx EarlyModuleContext) SdkSpec