Adds support for item use scripts

src/dynamic_data/script_handling/item_script.rs

@@ -1,2 +1,46 @@
+use crate::dynamic_data::Pokemon;
+use crate::static_data::EffectParameter;
+use std::sync::Arc;
+
 /// The script functions that are relevant to item use.
-pub trait ItemScript {}
+pub trait ItemScript {
+    /// Initializes the script with the given parameters for a specific item
+    fn on_initialize(&self, _pars: Vec<Arc<EffectParameter>>) -> anyhow_ext::Result<()> {
+        Ok(())
+    }
+
+    /// Returns whether the item is usable in the current context.
+    fn is_item_usable(&self) -> anyhow_ext::Result<bool> {
+        Ok(false)
+    }
+
+    /// Returns whether the item requires a target to be used.
+    fn requires_target(&self) -> anyhow_ext::Result<bool> {
+        Ok(false)
+    }
+
+    /// Returns whether the item is usable on the given target.
+    fn is_target_valid(&self, _target: &Pokemon) -> anyhow_ext::Result<bool> {
+        Ok(false)
+    }
+
+    /// Returns whether the item can be held by the given target.
+    fn is_holdable(&self) -> anyhow_ext::Result<bool> {
+        Ok(false)
+    }
+
+    /// Returns whether the item can be held by the given target.
+    fn can_target_hold(&self, _target: &Pokemon) -> anyhow_ext::Result<bool> {
+        Ok(false)
+    }
+
+    /// Handles the use of the item.
+    fn on_use(&self) -> anyhow_ext::Result<()> {
+        Ok(())
+    }
+
+    /// Handles the use of the item on the given target.
+    fn on_use_with_target(&self, _target: &Pokemon) -> anyhow_ext::Result<()> {
+        Ok(())
+    }
+}