flagd-web-provider should fire an event on reconnect

We probably want to fire a `configuration_changed` event on reconnect, in case any events have been missed. To keep things from being too chatty, we can do this only if we're currently in a reconnecting state, so that we don't get a redundant event with the initial ready.

https://github.com/open-feature/js-sdk-contrib/blob/main/libs/providers/flagd-web/src/lib/flagd-web-provider.ts#L121-L124