feat: exec mode improvements

Use Bollard library to exec in pure Rust.

`--use-cli` cli arg, will then only try to exec into containers using
Docker.

Only try to exec into a container if the state == Running.

src/app_data/mod.rs

@@ -83,7 +83,7 @@ impl AppData {
 
     #[cfg(debug_assertions)]
     #[allow(unused)]
-    pub fn set_debug_string(&mut self, x: &str) {
+    pub fn push_debug_string(&mut self, x: &str) {
         self.debug_string.push_str(x);
     }
 
@@ -506,6 +506,12 @@ impl AppData {
         self.get_selected_container().map(|i| i.id.clone())
     }
 
+    /// Get the Id and State for the currently selected container - used by the exec check method
+    pub fn get_selected_container_id_state(&self) -> Option<(ContainerId, State)> {
+        self.get_selected_container()
+            .map(|i| (i.id.clone(), i.state))
+    }
+
     /// Update container mem, cpu, & network stats, in single function so only need to call .lock() once
     /// Will also, if a sort is set, sort the containers
     pub fn update_stats(