feat(runloop): plugin:configure(configs) handler

### Summary

Adds a new handler that plugins can implement:

```
 -- configs will be `nil` if there is no active configs for the plugin
function Plugin:configure(configs)
end
```

See the change in `acme` plugin.

Signed-off-by: Aapo Talvensaari <[email protected]>

kong/plugins/acme/client.lua

@@ -508,20 +508,10 @@ local function renew_certificate_storage(conf)
 
 end
 
-local function renew_certificate(premature)
-  if premature then
-    return
-  end
-
-  for plugin, err in kong.db.plugins:each(1000) do
-    if err then
-      kong.log.warn("error fetching plugin: ", err)
-    end
-
-    if plugin.name == "acme" then
-      kong.log.info("renew storage configured in acme plugin: ", plugin.id)
-      renew_certificate_storage(plugin.config)
-    end
+local function renew_certificate(configs)
+  for _, config in ipairs(configs) do
+    kong.log.info("renew storage configured in acme plugin: ", config.__plugin_id)
+    renew_certificate_storage(config)
   end
 end
 

kong/plugins/acme/handler.lua

@@ -70,10 +70,22 @@ local domains_matcher
 -- expose it for use in api.lua
 ACMEHandler.build_domain_matcher = build_domain_matcher
 
+
+local CONFIGS
+
+
+local function renew(premature)
+  if premature or not CONFIGS then
+    return
+  end
+  client.renew_certificate(CONFIGS)
+end
+
+
 function ACMEHandler:init_worker()
   local worker_id = ngx.worker.id()
   kong.log.info("acme renew timer started on worker ", worker_id)
-  ngx.timer.every(86400, client.renew_certificate)
+  ngx.timer.every(86400, renew)
 
   -- handle cache updating of domains_matcher
   kong.worker_events.register(function(data)
@@ -92,6 +104,12 @@ function ACMEHandler:init_worker()
   end, "crud", "plugins")
 end
 
+
+function ACMEHandler:configure(configs)
+  CONFIGS = configs
+end
+
+
 local function check_domains(conf, host)
   if not conf.enable_ipv4_common_name and string_find(host, "^(%d+)%.(%d+)%.(%d+)%.(%d+)$") then
     return false