network: fix 8021x cert file path issue if contains unicode

- Fix unicode issue and append test cases

- Complete DebugListKeyDetail for connection session

- Refactor test code, move test variables to there place

tower: https://tower.im/projects/15081ba156b14fa4bd6d9e82f91edff3/todos/78392eb2934a4dd9a06f9bfd9ce3bd5e/
Change-Id: I77fc349bfcc1de6248d0e94f493c6c3bc85d976c