feat: replaced `kytos/mef_eline.loaded` with `kytos/mef_eline.evcs_loaded`

[viniarck]

Closes #66

This PR is on top of PR #67

This PR depends on https://github.com/kytos-ng/mef_eline/pull/401

Summary

• feat: replaced kytos/mef_eline.loaded with kytos/mef_eline.evcs_loaded
• This NApp hasn't been released yet no need to update changelog

Local Tests

• Created with INT EVCs and restarted, the expected srcs_pp (source proxy ports) were correctly loaded too:

kytos $> controller.napps[('kytos', 'telemetry_int')].int_manager.srcs_pp                                                                                                                
    ...:                                                                                                                                                                                 
Out[1]: 
{'00:00:00:00:00:00:00:01:5': ProxyPort(Interface('s1-eth5', 5, Switch('00:00:00:00:00:00:00:01')), Interface('s1-eth6', 6, Switch('00:00:00:00:00:00:00:01')), EntityStatus.UP),
 '00:00:00:00:00:00:00:01:7': ProxyPort(Interface('s1-eth7', 7, Switch('00:00:00:00:00:00:00:01')), Interface('s1-eth8', 8, Switch('00:00:00:00:00:00:00:01')), EntityStatus.UP),
 '00:00:00:00:00:00:00:03:5': ProxyPort(Interface('s3-eth5', 5, Switch('00:00:00:00:00:00:00:03')), Interface('s3-eth6', 6, Switch('00:00:00:00:00:00:00:03')), EntityStatus.UP)}

kytos $> srcs_pp = controller.napps[('kytos', 'telemetry_int')].int_manager.srcs_pp                                                                                                      
    ...:                                                                                                                                                                                 

kytos $> srcs_pp['00:00:00:00:00:00:00:01:5'].evc_ids                                                                                                                                    
Out[3]: {'735fa71d2f4f4d', 'a928a2bbfb4d47'}

End-to-End Tests

N/A yet

[viniarck]

LGTM

Appreciated your review, Italo.