Middleware: Add CSP support (#29740)

* Middleware: Add support for CSP

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored by @iOrcohen

pkg/models/context.go

@@ -19,6 +19,8 @@ type ReqContext struct {
 	AllowAnonymous bool
 	SkipCache      bool
 	Logger         log.Logger
+	// RequestNonce is a cryptographic request identifier for use with Content Security Policy.
+	RequestNonce string
 }
 
 // Handle handles and logs error by given status.