Add loader and sceanrio runner interfaces, add support for local scenario

Signed-off-by: Andrey Berezin <a.berezin@yadro.com>

src/frostfs_testlib/load/loaders.py

@@ -0,0 +1,60 @@
+from frostfs_testlib.load.interfaces import Loader
+from frostfs_testlib.resources.load_params import (
+    LOAD_NODE_SSH_PASSWORD,
+    LOAD_NODE_SSH_PRIVATE_KEY_PASSPHRASE,
+    LOAD_NODE_SSH_PRIVATE_KEY_PATH,
+    LOAD_NODE_SSH_USER,
+)
+from frostfs_testlib.shell.interfaces import Shell, SshCredentials
+from frostfs_testlib.shell.ssh_shell import SSHShell
+from frostfs_testlib.storage.cluster import ClusterNode
+
+
+class RemoteLoader(Loader):
+    def __init__(self, ssh_credentials: SshCredentials, ip: str) -> None:
+        self.ssh_credentials = ssh_credentials
+        self._ip = ip
+
+    @property
+    def ip(self):
+        return self._ip
+
+    def get_shell(self) -> Shell:
+        ssh_client = SSHShell(
+            host=self.ip,
+            login=self.ssh_credentials.ssh_login,
+            password=self.ssh_credentials.ssh_password,
+            private_key_path=self.ssh_credentials.ssh_key_path,
+            private_key_passphrase=self.ssh_credentials.ssh_key_passphrase,
+        )
+
+        return ssh_client
+
+    @classmethod
+    def from_ip_list(cls, ip_list: list[str]) -> list[Loader]:
+        loaders: list[Loader] = []
+        ssh_credentials = SshCredentials(
+            LOAD_NODE_SSH_USER,
+            LOAD_NODE_SSH_PASSWORD,
+            LOAD_NODE_SSH_PRIVATE_KEY_PATH,
+            LOAD_NODE_SSH_PRIVATE_KEY_PASSPHRASE,
+        )
+
+        for ip in ip_list:
+            loaders.append(RemoteLoader(ssh_credentials, ip))
+
+        return loaders
+
+
+class NodeLoader(Loader):
+    """When ClusterNode is the loader for itself (for Local scenario only)."""
+
+    def __init__(self, cluster_node: ClusterNode) -> None:
+        self.cluster_node = cluster_node
+
+    def get_shell(self) -> Shell:
+        return self.cluster_node.host.get_shell()
+
+    @property
+    def ip(self):
+        return self.cluster_node.host_ip