AIDEGen: Remove unused methods from the project_file_gen.py.

1. Remove the methods for generating iml file.
2. Move the test case for get_uniqe_iml_name() from
   lib/project_file_gen_unittest.py to .idea/iml_unittest.py

Bug: 154436905
Test: sh run_tests.sh;atest aidegen_unittests --host
Change-Id: I1af7792fc60cf4c2988df56a7df82267cccb5dfe
3 files changed