[SPARK-36910][PYTHON] Inline type hints for python/pyspark/sql/types.py

### What changes were proposed in this pull request?
Inline type hints for python/pyspark/sql/types.py

### Why are the changes needed?
Current stub files cannot support type checking for the function body. Inline type hints can type check the function body.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
Existing tests.

Closes apache#34174 from xinrong-databricks/inline_types.

Authored-by: Xinrong Meng <[email protected]>
Signed-off-by: Takuya UESHIN <[email protected]>

Author: xinrong-meng

python/pyspark/pandas/frame.py

@@ -6417,12 +6417,14 @@ def select_dtypes(
         """
         from pyspark.sql.types import _parse_datatype_string  # type: ignore[attr-defined]
 
+        include_list: List[str]
         if not is_list_like(include):
-            include_list = [include] if include is not None else []
+            include_list = [cast(str, include)] if include is not None else []
         else:
             include_list = list(include)
+        exclude_list: List[str]
         if not is_list_like(exclude):
-            exclude_list = [exclude] if exclude is not None else []
+            exclude_list = [cast(str, exclude)] if exclude is not None else []
         else:
             exclude_list = list(exclude)
 

python/pyspark/sql/dataframe.py

@@ -310,7 +310,8 @@ def schema(self) -> StructType:
         """
         if self._schema is None:
             try:
-                self._schema = _parse_datatype_json_string(self._jdf.schema().json())
+                self._schema = cast(
+                    StructType, _parse_datatype_json_string(self._jdf.schema().json()))
             except Exception as e:
                 raise ValueError(
                     "Unable to parse datatype from schema. %s" % e) from e

python/pyspark/sql/session.py

@@ -790,7 +790,7 @@ def createDataFrame(  # type: ignore[misc]
             raise TypeError("data is already a DataFrame")
 
         if isinstance(schema, str):
-            schema = _parse_datatype_string(schema)
+            schema = cast(Union[AtomicType, StructType, str], _parse_datatype_string(schema))
         elif isinstance(schema, (list, tuple)):
             # Must re-encode any unicode strings to be consistent with StructField names
             schema = [x.encode('utf-8') if not isinstance(x, str) else x for x in schema]