Updated interface for uSockets#231

[partyblob]

Provides an updated App options interface to allow specifying in-memory cert/key data rather than filepath (filepath is still the default)

Provides TemplatedApp::setOptions(const SocketContextOptions& options) to change server options while the server is running (i.e avoid add_server_name workaround which does not work for situations like wildcard or shared certificates)

For more info see the upstream PR