Add ssltransport for robovacs (#943)

This PR implements a clear-text, token-based transport protocol seen on
RV30 Plus (#937).

- Client sends `{"username": "email@example.com", "password":
md5(password)}` and gets back a token in the response
- Rest of the communications are done with POST at `/app?token=<token>`

---------

Co-authored-by: Steven B. <51370195+sdb9696@users.noreply.github.com>

kasa/transports/__init__.py

@@ -3,11 +3,13 @@
 from .aestransport import AesEncyptionSession, AesTransport
 from .basetransport import BaseTransport
 from .klaptransport import KlapTransport, KlapTransportV2
+from .ssltransport import SslTransport
 from .xortransport import XorEncryption, XorTransport
 
 __all__ = [
     "AesTransport",
     "AesEncyptionSession",
+    "SslTransport",
     "BaseTransport",
     "KlapTransport",
     "KlapTransportV2",