Add .fetchindex signal for refreshing the package index

src/main.rkt

@@ -2,6 +2,7 @@
 
 (module+ main
   (require "entrypoint.rkt")
+  (void (make-entry-point 'refresh-packages! "packages.rkt"))
   (start-service #:reloadable? (getenv "SITE_RELOADABLE")
                  (make-entry-point 'request-handler "site.rkt")
                  (make-entry-point 'on-continuation-expiry "site.rkt")))

src/signals.rkt

@@ -29,5 +29,8 @@
        (poll-signal "../signals/.reload"
                     "Reload signal received - attempting to reload code"
                     (lambda () (reload!)))
+       (poll-signal "../signals/.fetchindex"
+                    "Index refresh signal received"
+                    (lambda () ((entry-point-value (lookup-entry-point 'refresh-packages!)))))
        (sleep 0.5)
        (loop)))))