Use `Query` type instead of `str`

[ikhoon]

#14 introduced Query type. The existing APIs that use a string as a query expression need to be updated such as.

centraldogma-python/centraldogma/content_service.py

Line 44 in 6098f1a

path_pattern: Optional[str],

centraldogma-python/centraldogma/query.py

Lines 30 to 45 in 6098f1a

	class Query(Generic[T]):
	@staticmethod
	def identity(path: str) -> Query[str]:
	return Query(path=path, query_type=QueryType.IDENTITY, expressions=[])
	@staticmethod
	def text(path: str) -> Query[str]:
	return Query(path=path, query_type=QueryType.IDENTITY_TEXT, expressions=[])
	@staticmethod
	def json(path: str) -> Query[Any]:
	return Query(path=path, query_type=QueryType.IDENTITY_JSON, expressions=[])
	@staticmethod
	def json_path(path: str, json_paths: List[str]) -> Query[Any]:
	return Query(path=path, query_type=QueryType.JSON_PATH, expressions=json_paths)