add encrption module

fix bug in zstd compression warp code
fix bug when showing compression inforamtion

game_backuper/_zstd.pyi

@@ -0,0 +1,15 @@
+def version() -> str: ...
+def maxCLevel() -> int: ...
+class ZSTDCompressor:  # noqa: E302
+    def __init__(self, compresslevel: int = 3): ...
+    def compress(self, inp: bytes) -> bytes: ...
+    def flush(self) -> bytes: ...
+class ZSTDDecompressor:  # noqa: E302
+    def __init__(self): ...
+    def decompress(self, data: bytes, max_length: int = -1) -> bytes: ...
+    @property
+    def eof(self) -> bool: ...
+    @property
+    def unused_data(self) -> bytes: ...
+    @property
+    def needs_input(self) -> bool: ...