feat(wit)!: add plugin-api/host-state-plugin#get-repl-var so that plugin can access a variable if they know the name

BREAKING CHANGE: break plugin-api backwards compatibility by changing
the wit contract

Author: topheman

crates/pluginlab/src/store.rs

@@ -82,6 +82,16 @@ impl crate::api::plugin_api::repl::api::http_client::Host for PluginHost {
     }
 }
 
+///
+impl crate::api::plugin_api::repl::api::host_state_plugin::Host for PluginHost {
+    async fn get_repl_var(&mut self, key: String) -> Option<String> {
+        None
+        // Can't do the following because `PluginHost` does not have access to repl_vars
+        // we need to add a repl_vars field to PluginHost that points to the repl_vars field of WasiState
+        // self.repl_vars.get(&key).cloned()
+    }
+}
+
 /// It is necessary to implement this trait on PluginHost because other parts rely on it.
 impl crate::api::plugin_api::repl::api::transport::Host for PluginHost {
     // This trait has no methods, so no implementation needed

crates/pluginlab/wit/plugin-api.wit

@@ -23,7 +23,12 @@ interface http-client {
   get: func(url: string, headers: list<http-header>) -> result<http-response, string>;
 }
 
+interface host-state-plugin {
+  get-repl-var: func(key: string) -> option<string>;
+}
+
 world plugin-api {
   import http-client;
+  import host-state-plugin;
   export plugin;
 }