Configparser to access nested attributes with dot notation

[wyli]

Is your feature request related to a problem? Please describe.
Follow up of #5804, since v1.2 PR #5813

data_file_base_dir = parser.data_file_base_dir

is an equivalent command of

data_file_base_dir = parser.get_parsed_content("data_file_base_dir")

which improves the code readability. However, the current implementation doesn't support nested structures such as parser.foo[0].bar.x.

This is a feature request for extending the dot notation for accessing the nested config structures.

please see also:

• a possible implementation to integrate: easydict https://github.com/makinacorpus/easydict/blob/master/easydict/__init__.py
• configparser usage https://github.com/Project-MONAI/MONAI/blob/dev/docs/source/config_syntax.md