add Docker credentials to app and CLI

src-tauri/migrations/20240919135710_docker_creds.sql

@@ -0,0 +1,11 @@
+CREATE TABLE docker_credentials (
+    id BLOB UNIQUE NOT NULL,
+    -- The Docker credential helper protocol only sends the server_url, so
+    -- we should guarantee that we will only ever have one matching credential.
+    -- Also, it's easier to go from unique -> not-unique than vice versa if we
+    -- decide that's necessary in the future
+    server_url TEXT UNIQUE NOT NULL,
+    username TEXT NOT NULL,
+    secret_enc BLOB NOT NULL,
+    nonce BLOB NOT NULL
+);