[adbwifi] Add adbwifi_libs, TLS connection, and MDNS implementation.

Bug: 111434128, 119493510, 119494503

Test: Enable wireless debugging in Settings UI, click "pair with pairing code"
to generate pairing code.
On client, 'adb pair <ip_address>', enter pairing code at prompt and hit
enter. Pairing should complete.
'adb logcat'.
Change-Id: I86527bd3fc52e30a8e08ec5843dc3e100abf91fa
Exempt-From-Owner-Approval: approved already
diff --git a/adb_auth.h b/adb_auth.h
index 2be9a76..09c3a2d 100644
--- a/adb_auth.h
+++ b/adb_auth.h
@@ -38,6 +38,7 @@
 int adb_auth_keygen(const char* filename);
 int adb_auth_pubkey(const char* filename);
 std::string adb_auth_get_userkey();
+bssl::UniquePtr<EVP_PKEY> adb_auth_get_user_privkey();
 std::deque<std::shared_ptr<RSA>> adb_auth_get_private_keys();
 
 void send_auth_response(const char* token, size_t token_size, atransport* t);