Fix "method_complexity" issue in Sources/AssetLib/Controllers/TemplateTypeParser.swift

[leogdion]

Function templateType has a Cognitive Complexity of 6 (exceeds 5 allowed). Consider refactoring.

https://codeclimate.com/github/brightdigit/AssetLib/Sources/AssetLib/Controllers/TemplateTypeParser.swift#issue_5e7e108a62c6af00010000cf