Make modules/context.Context a context.Context (#16031)

* Make modules/context.Context a context.Context

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Simplify context calls

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Set the base context for requests to the HammerContext

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/events/events.go

@@ -42,7 +42,7 @@ func Events(ctx *context.Context) {
 	}
 
 	// Listen to connection close and un-register messageChan
-	notify := ctx.Req.Context().Done()
+	notify := ctx.Done()
 	ctx.Resp.Flush()
 
 	shutdownCtx := graceful.GetManager().ShutdownContext()