Created by: liym27

switch api 增强输入类型检查

switch_case(branch_index, branch_fns, default=None, name=None)

1. 检查branch_index:

   • 检查类型是否为Variable
   • 检查数据类型是否为"uint8", "int32", "int64"

2. 检查branch_fns:

   • 检查类型是否为 list, tuple, dict

TypeError: The type of 'branch_fns' in switch_case must be (<type 'list'>, <type 'tuple'>, <type 'dict'>), but received <type 'int'>.

注：该api原本的报错信息已很完善，本PR尽可能将类型检查统一用check_variable_and_dtype和check_type接口。无法统一到上述2个接口的，不做修改。