lib/api: Allow Bearer authentication style with API key (#9002)

Currently, historically, we look for the `X-API-Key` header to
authenticate with an API key. There's nothing wrong with this, but in
some scenarios it's easier to produce an `Authorization` header with a
`Bearer $token` content, which is nowadays more common. This change adds
support for both, so that we will accept an API key either in our custom
header or as a bearer token.

lib/api/api_auth.go

@@ -39,7 +39,7 @@ func emitLoginAttempt(success bool, username, address string, evLogger events.Lo
 
 func basicAuthAndSessionMiddleware(cookieName string, guiCfg config.GUIConfiguration, ldapCfg config.LDAPConfiguration, next http.Handler, evLogger events.Logger) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if guiCfg.IsValidAPIKey(r.Header.Get("X-API-Key")) {
+		if hasValidAPIKeyHeader(r, guiCfg) {
 			next.ServeHTTP(w, r)
 			return
 		}