Fix bug in filepath_manager (about processing without output dir as parameter)

.gitignore

amrbatch/filepath_manager.py

tests/amrbatch.log

tests/input/08d1b73a-bdf5-4b54-8e6e-b96665f3c2fa.txt

tests/output/Test-20230306/test-01/test-01.stog.amr.dot

tests/output/Test-20230306/test-01/test-01.stog.amr.nt

tests/output/Test-20230306/test-01/test-01.stog.amr.penman

tests/output/Test-20230306/test-01/test-01.stog.amr.png

tests/output/Test-20230306/test-01/test-01.stog.amr.ttl

tests/output/Test-20230306/test-02/test-02.stog.amr.dot

tests/output/Test-20230306/test-02/test-02.stog.amr.nt

tests/output/Test-20230306/test-02/test-02.stog.amr.penman

tests/output/Test-20230306/test-02/test-02.stog.amr.png

tests/output/Test-20230306/test-02/test-02.stog.amr.ttl

tests/output/Test-20230306/test.sentence.txt

tests/test_amrbatch_main.py