TLS cipher suite hardcoded to AES-128-GCM-SHA256

[pawelchcki]

Hi!

src/client.rs hardcodes Aes128GcmSha256 in the CryptoProvider impl,
the TlsConnection<_,_,..> type, and the HttpConnection::Tls variant
(L67, L205, L304). The ClientHello only ever offers TLS_AES_128_GCM_SHA256,
so servers that don't accept it can't complete a handshake.

Hits me on one of backend entrypoints offering only TLS_AES_256_GCM_SHA384. Likely
also the root cause of #96.

Other than probably some larger refactoing - I can add a quick pr aes256-sha384 feature that swaps the suite via a
private type alias?

[alloncm]

I'm experiencing this too, sounds like a good quick fix

[lulf]

PRs welcome!

[pawelchcki]

I added https://github.com/drogue-iot/reqwless/pull/135/changes - but I don't like it :P . If you have @lulf any suggestion how you would like to see configurability here I could try making something nicer.

[lulf]

It's not 'pretty', but this is the cost of writing stuff for embedded in rust :) I think this is OK for now. It primarily impacts maintainers of the crate. The alternative is to make this configurable via some generic, which more impacts the users of the crate.