Prior to this commit, the WebSocket endpoint (MVC or WebFlux) would be
enabled by default. In the case of MVC, the presence of
`spring-websocket` and the required dependencies was an additional hint
that could enable/disable this support depending on the application.
This commit changes the websocket path configuration so that it doesn't
hold a default value anymore. Configuring this property will trigger the
WebSocket support.
Right now developers cannot configure it to be the same as the
`spring.graphql.path`, but this will be solved in #30.
This commit also revisits the configuration properties namespace for
clarity, moving the websocket bits under their own section.
Closes gh-31
36121f338f