fix annotation key-error

[Crysple]

Overview

Related to #801

When use annotation in a file in a sub-directory and import it from the main program, there's a search space key inconsistency between search space generator and NNI sdk. The latter one use inspect library to get module name in a wrong way (without importing path)

Background

Note that NNI's annotation variable consists of three parts like:
key = '{}/{}/{}'.format(module, name, function_type)
where the first one is the module path of the file that uses annotation, the second one is the annotated variable name given by user, and the third one is the search space type like choice or uniform. Below we only consider the module part of its key.

Comparison

For example, if the main program is main.py and users use annotation in subpkg_main.py, their key is:

• NNI API:
  • Before fix: subpkg_main
  • After fix: subpkg.subpkg_main
• Search Space Generator:
  • Before fix: subpkg.subpkg_main
  • After fix: subpkg.subpkg_main

├── main.py
└── subpkg
    ├── __init__.py
    └──  subpkg_main.py

[QuanluZhang]

@Crysple let's rethink the construction of the key.

[QuanluZhang]

looks good

[Crysple]

Waive for further unit test modification