Move out template meta comment parsing to "TemplateCommentParser" class

Plan:

1. create the "TemplateCommentParser" class, that: - 0.2h
   • would accept path to template as constructor argument
   • the "parse" method would return associative array of results
2. add support for data types in the class: - 0.5h
   • "string" - any string
   • "boolean" - true (when "yes"), false (when "no"), exception otherwise
   • "integer" - as-as, when a positive integer, exception otherwise
   • "category_path" - would split value by "||" and trim each each element
3. define supported settings and their data types as class properties (similar to "Fields" array in unit config with "type" and "default") - 0.3h
4. when template doesn't exist throw an exception - 0.1h
5. add "getDefaults" method, that will return an array (keys - field names, values - their default values) - 0.5h
6. when no meta comment found, then return result of calling "getDefaults" method - 0.1h
7. when meta comment found: - 0.3h
   • if it's one line long, then return an result of calling "getDefaults" method
   • if it's invalid XML, then throw an exception
   • when unsupported setting found, then throw an exception
   • when supported setting found, but it has value unknown format, then throw an exception
8. return parsing result (if some fields not present, then add them with their default values)
9. delete "kThemesHelper::parseTemplateMetaInfo" in favor of using "TemplateCommentParser::parse" method - 0.5h