Add exec_run implementation for containers

This change adds a basic implementation of exec_run for containers
Environment variable conversions are handled from dict->list[str]
DetachKeys will need an actual argument option
detach, stream, socket, and demux arguments are currently not handled.

podman/domain/containers.py

@@ -130,7 +130,7 @@ def exec_run(
         stdout: bool = True,
         stderr: bool = True,
         stdin: bool = False,
-        tty: bool = False,
+        tty: bool = True,
         privileged: bool = False,
         user=None,
         detach: bool = False,
@@ -170,10 +170,34 @@ def exec_run(
             NotImplementedError: method not implemented.
             APIError: when service reports error
         """
-        if user is None:
-            user = "root"
-
-        raise NotImplementedError()
+        user = user or "root"
+        if isinstance(environment, dict):
+            environment = [f"{k}={v}" for k, v in environment.items()]
+        data = {
+            "AttachStderr": stderr,
+            "AttachStdin": stdin,
+            "AttachStdout": stdout,
+            "Cmd": cmd if isinstance(cmd, list) else cmd.split(),
+            # "DetachKeys": detach,  # This is something else
+            "Env": environment,
+            "Privileged": privileged,
+            "Tty": tty,
+            "User": user,
+            "WorkingDir": workdir
+        }
+        # create the exec instance
+        response = self.client.post(f"/containers/{self.name}/exec", data=json.dumps(data))
+        response.raise_for_status()
+        exec_id = response.json()['Id']
+        # start the exec instance
+        response = self.client.post(f"/exec/{exec_id}/start", data=json.dumps(
+            {"Detach": detach, "Tty": tty}
+        ))
+        response.raise_for_status()
+        # get and return exec information
+        response = self.client.get(f"/exec/{exec_id}/json")
+        response.raise_for_status()
+        return response.json().get('ExitCode')
 
     def export(self, chunk_size: int = api.DEFAULT_CHUNK_SIZE) -> Iterator[bytes]:
         """Download container's filesystem contents as a tar archive.