Add support to str for dl_type

[Alopalao]

Related to mef_eline PR #258

Summary

dl_type in a flow can now accept string values

Local Tests

Flow received

2023-02-08 12:30:40,999 - INFO [kytos.napps.kytos/flow_manager] (thread_pool_sb_1) Flow forwarded to switch 00:00:00:00:00:00:00:01 to be deleted. Flow: {'flows': [{'switch': '00:00:00:00:00:00:00:01', 'table_id': 0, 'match': {'in_port': 1, 'dl_vlan': '0/0'}, 'priority': 20000, 'idle_timeout': 0, 'hard_timeout': 0, 'cookie': 12263066888382572876, 'id': '743158efbd47ba03670cc9c8478ce6ec', 'stats': {'byte_count': 0, 'duration_sec': 33, 'duration_nsec': 64000000, 'packet_count': 0}, 'cookie_mask': 0, 'instructions': [{'instruction_type': 'apply_actions', 'actions': [{'action_type': 'push_vlan', 'tag_type': 's'}, {'vlan_id': 24, 'action_type': 'set_vlan'}, {'port': 2, 'action_type': 'output'}]}]}]}

REMINDER: Tests missing.

[viniarck]

Aldo thanks for anticipating some work on this functionality.

Please, check out comment kytos-ng/mef_eline#258 (comment)

I think we'll need to adapt and evolve things here.

[Alopalao]

Another PR is handling this case better. Closing.