Created tests for new api requests

[Alopalao]

Closes #330

Summary

Introduced tests for

• Error 404 POST /api/kytos/flow_manager/v2/flows_by_switch/
• Error 404 POST /api/kytos/flow_manager/v2/flows and a list of switches
• Installation and deletion for /api/kytos/flow_manager/v2/flows_by_switch/
• Installation and deletion for /api/kytos/flow_manager/v2/flows and a list of switches

Local Tests

N/A

End-to-End Tests

+ python3 -m pytest tests/ -k 'test_085_install_flows_by_switch_but_404 or test_090_install_flows_in_switch_list_but_404 or test_095_install_delete_flows_by_switch or test_100_install_delete_flows_in_switch_list' --reruns 0 -r fEr
============================= test session starts ==============================
platform linux -- Python 3.11.2, pytest-8.1.1, pluggy-1.5.0
rootdir: /tests
plugins: rerunfailures-13.0, timeout-2.2.0, anyio-4.3.0
collected 271 items / 267 deselected / 4 selected

tests/test_e2e_20_flow_manager.py ....                                   [100%]

All the e2e tests to be added