Added dismissible alert plugin

This is the cleaned up version of https://github.com/wet-boew/wet-boew/pull/5932.
Please note the build will fail because of this issue: https://github.com/wet-boew/wet-boew/issues/5927
The problem with that is init gets called for each details/summary so that function call would be executed each time as well (so would be binding over and over again). Best to bind only once (or to only do that function call only once). A way to make that work would be to have a boolean global to the plugin that is checked on each init to ensure it only fires once). Although I'm not sure that would be as efficient as the timerpoke approach (I'm fine with whatever is the most efficient from a performance standpoint).