Added missing type hints (#55)

* Added missing type hints

* Reformatted

amulet_nbt/_compound.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Iterable
+from typing import Any, Dict, Iterable, Iterator
 from collections.abc import MutableMapping
 
 from ._value import AbstractBaseMutableTag, AbstractBaseTag
@@ -52,3 +52,8 @@ class CompoundTag(AbstractBaseMutableTag, MutableMapping[str, AnyNBT]):
     def setdefault_long_array(
         self, key: str, default: LongArrayTag = None
     ) -> LongArrayTag: ...
+    def __getitem__(self, item: str) -> AnyNBT: ...
+    def __setitem__(self, key: str, value: AnyNBT) -> None: ...
+    def __delitem__(self, item: str) -> None: ...
+    def __iter__(self) -> Iterator[str]: ...
+    def __len__(self) -> int: ...

amulet_nbt/_list.pyi

@@ -1,4 +1,4 @@
-from typing import Iterable, overload, List, TypeVar
+from typing import Iterable, overload, List, TypeVar, overload
 from collections.abc import MutableSequence
 
 from ._value import AbstractBaseMutableTag
@@ -33,3 +33,8 @@ class ListTag(AbstractBaseMutableTag, MutableSequence[AnyNBTT]):
     def get_byte_array(self, index: int) -> ByteArrayTag: ...
     def get_int_array(self, index: int) -> IntArrayTag: ...
     def get_long_array(self, index: int) -> LongArrayTag: ...
+    def __getitem__(self, item: int) -> AnyNBTT: ...
+    def __setitem__(self, key: int, value: AnyNBTT) -> None: ...
+    def __delitem__(self, key: int) -> None: ...
+    def __len__(self) -> int: ...
+    def insert(self, index: int, item: AnyNBTT) -> None: ...