Rename module -> module-lib

When sdk_version: "module_current" in an unbundled build, previously
prebuilt/sdk/current/module/android.jar was used. But that path is
wrong; we have prebuilt/sdk/current/module-lib/android.jar for the
module APIs. Fix the mismatch by changing the string name of the module
API from "module" to "module-lib".

Also, "system_server" for system server API is changed to
"system-server" to match with the path
/prebuilts/sdk/current/system-server/.

Bug: N/A
Test: https://android-build.googleplex.com/builds/forrest/run/L86100000601675127
Change-Id: I23e9befbd9592d3b22989c2c8fbf34d434273288