Add Mangacollec icon

[apix0n]

Issue: closes #12117

Popularity metric:

• Similarweb rank is 180,470 -- https://similarweb.com/website/mangacollec.com
• Android app has 100k+ downloads; see https://play.google.com/store/apps/details?id=com.mangacollec

Checklist

• I have reviewed the forbidden brands list and confirm the brand I am submitting a PR for is not one of them, nor is it a subsidiary of one of those brands
• I have reviewed the brand's terms of service, and am confident we can add this icon
• I updated the JSON data in data/simple-icons.json
• I optimized the icon with SVGO or SVGOMG
• The SVG viewbox is 0 0 24 24

Description

• Got the icon at https://www.mangacollec.com/favicon.svg
• Selected the accent colour from the iOS and Android app icons (as 99% of the users use the app instead of the website)