add messaging feedback receive event to facebookapp handler

[rasoro]

support to receive messaging_feedback webhook event on facebookapp handler, from response of a customer feedback template.

with this, rapidpro can receive the result as question payload from customer answer.

reference: https://developers.facebook.com/docs/messenger-platform/send-messages/templates/customer-feedback-template/

edit1:
add support to send customer feedback template from send message with a specifc protocol.

{customer_feedback_template}|
title: Avalie sua experiência conosco|
subtitle:nos ajude a melhorar a eficiência do serviço|
button_title:Avaliar|
question_title:Como foi sua experiência na conversa?|
question_id:definida_pelo_usuario|
type:csat|
score_label:neg_pos|
score_option:five_stars|
business_privacy:www.example.com

[codecov-commenter]

Codecov Report

Merging #82 (79faf8f) into main (8d70f22) will decrease coverage by 0.44%.
The diff coverage is 16.17%.

@@            Coverage Diff             @@
##             main      #82      +/-   ##
==========================================
- Coverage   71.51%   71.07%   -0.45%     
==========================================
  Files          95       95              
  Lines        8444     8512      +68     
==========================================
+ Hits         6039     6050      +11     
- Misses       1788     1843      +55     
- Partials      617      619       +2     

Impacted Files	Coverage Δ
handlers/facebookapp/facebookapp.go	66.76% <16.17%> (-13.24%)	⬇️

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