Added high-level abstraction for some PUS services

Introduced high-level abstractions for targetable requests in general.

- PUS Service 3 (HK) abstraction for targetable HK requests
- PUS Service 8 (Action) abstraction for targetable action requests

satrs/src/action.rs

@@ -0,0 +1,42 @@
+use crate::{pool::StoreAddr, TargetId};
+
+pub type ActionId = u32;
+
+#[non_exhaustive]
+#[derive(Clone, Eq, PartialEq, Debug)]
+pub enum ActionRequest {
+    UnsignedIdAndStoreData {
+        action_id: ActionId,
+        data_addr: StoreAddr,
+    },
+    #[cfg(feature = "alloc")]
+    UnsignedIdAndVecData {
+        action_id: ActionId,
+        data: alloc::vec::Vec<u8>,
+    },
+    #[cfg(feature = "alloc")]
+    StringIdAndVecData {
+        action_id: alloc::string::String,
+        data: alloc::vec::Vec<u8>,
+    },
+    #[cfg(feature = "alloc")]
+    StringIdAndStoreData {
+        action_id: alloc::string::String,
+        data: StoreAddr,
+    },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TargetedActionRequest {
+    target: TargetId,
+    action_request: ActionRequest,
+}
+
+impl TargetedActionRequest {
+    pub fn new(target: TargetId, action_request: ActionRequest) -> Self {
+        Self {
+            target,
+            action_request,
+        }
+    }
+}