Added favicon support for safari

[Mcrich23]

As with favicon support before (#8, #9), safari was not supported. This pr should fix that.

[twostraws]

This has been sitting waiting review for a while, which is my fault – I got into a bit of a rabbit hole on what exactly modern favicon support looks like, and in doing so even updated https://www.hackingwithswift.com to include the latest recommended approach. It's hard to get a great answer because so much just seems to be 10 years old, but from what I can see a good approach is:

1. Using an SVG for the main favicon
2. Using a 180x180 PNG for the Apple touch icon

I have no idea whether using 1 automatically makes 2 work, because if it doesn't it really ought to!

However, I'm wondering whether a better solution might work here: can we detect what favicon files they have in their Assets folder, and use that to generate all the correct tags automatically?

[Mcrich23]

we can. I was looking at this as well and apple requires an extra metatag for safari. Thats what this pr is for. If you want me to, I can set it to auto look for favicon.png/svg/jpeg, and then people can override it if they choose.

[aduryagin]

apple requires an extra metatag for safari

Worth to mention that apple-touch-icon has been deprecated. Apple requires this only for Safari versions prior to 15.4
Google Lighthouse also deprecated apple-touch-icon audit

GoogleChrome/lighthouse#14243
https://developer.apple.com/documentation/safari-release-notes/safari-15_4-release-notes#Web-API
https://developer.mozilla.org/en-US/docs/Web/Manifest/icons#browser_compatibility