[unittests] Add tests for the new algorithm APIs

beat/backend/python/algorithm.py

beat/backend/python/data_loaders.py

beat/backend/python/loader.py

...ckend/python/test/prefix/algorithms/autonomous/add/1.json

...backend/python/test/prefix/algorithms/autonomous/add/1.py

...kend/python/test/prefix/algorithms/autonomous/add2/1.json

...ackend/python/test/prefix/algorithms/autonomous/add2/1.py

...kend/python/test/prefix/algorithms/autonomous/add3/1.json

...ackend/python/test/prefix/algorithms/autonomous/add3/1.py

...kend/python/test/prefix/algorithms/autonomous/echo/1.json

...ackend/python/test/prefix/algorithms/autonomous/echo/1.py

...ython/test/prefix/algorithms/autonomous/no_prepare/1.json

.../python/test/prefix/algorithms/autonomous/no_prepare/1.py

.../python/test/prefix/algorithms/autonomous/no_setup/1.json

...nd/python/test/prefix/algorithms/autonomous/no_setup/1.py

...hon/test/prefix/algorithms/autonomous/parametrized/1.json

...ython/test/prefix/algorithms/autonomous/parametrized/1.py

...on/test/prefix/algorithms/autonomous/prepare_crash/1.json

...thon/test/prefix/algorithms/autonomous/prepare_crash/1.py

...hon/test/prefix/algorithms/autonomous/prepare_fail/1.json