Allow line comments for PR alert type

[eleftherias]

Enhance the PR alert type to allow Minder to leave comments on specific lines.

Given I have a rule in a profile with the alert type pull_request_comment
and I've defined the line_comments in my alert as follows

line_comments: 
     - filepath: home/path1.yaml 
       lineStart: 110
       lineEnd: 110
       comment: This dependency needs to be updated
     - filepath: home/path2.xml
       lineStart: 120
       lineEnd: 130
       comment: These lines of code need to be updated

then Minder comments on line 110 of the file home/path1.yaml with the message "This dependency needs to be updated"
and Minder comments on lines 120 to 130 of the file home/path2.xml with the message "These lines of code need to be updated"

Out of scope:

• Reading the output of the evaluation
• Gitlab