rdsys Intergration with WebTunnel

Now that we have finished uploading the connection information to rdsys, it is rdsys's turn to interpret and distribute this data.

Conceptually, WebTunnel should work in a way similar to obfs4 when it comes to bridge distribution

Tasks:

• add bridgestrap support for webtunnel bridges
• deploy webtunnel binary and supported bridgestrap in polyanthum
• configure rdsys to assign webtunnel bridges to http distributor
• modify bridgedb to add webtunnel selector in the http distributor
• deploy new bridgedb
• setup a test webtunnel bridge and check it gets distributed