Entitlement rotation support

Updates also include:
- Add APIs to query current Simulcrypt channel & stream status;
- EMM format change (used only to carry fingerprinting and service
blocking info);
- Key fetcher example to use curl key fetcher.

example/BUILD

@@ -62,6 +62,7 @@ cc_binary(
     srcs = ["wv_cas_key_fetcher_example.cc"],
     deps = [
         "//common:status",
+        "//media_cas_packager_sdk/public:wv_cas_curl_key_fetcher",
         "//media_cas_packager_sdk/public:wv_cas_key_fetcher",
     ],
 )