[manifest] Allow using metatags instead of JSON (#350)

I've implemented manifest on app.ft.com (it's not live yet), and my feedback is:

* The basic properties we needed (name and start URL) are redundant with numerous `<meta>` and `<link>` elements we have already.

* JSON is unpleasant to work with. It's unsuitable for manual authoring due to lack of comments and draconian XML-like error handling, but having to use a serializer for just a couple of properties feels silly, especially that we've had code to serialize metadata already — in HTML.

* external file feels unnecessary given how tiny it is.

* Adding a few more `<meta>` elements is *not a problem at all* for us, because when they're surrounded by very similar markup they gzip to almost zero. We already emit `<meta>` and `<link>` elements for "legacy" specs, social media sites, and vendor-specific features.

So overall I'd strongly prefer an option to use `<meta>` and `<link>` equivalents for basic Manifest features, to reduce overhead (both on-the-wire overhead due to inlined gzipped data, and maintenance overhead thanks to reusing existing HTML-meta pipeline instead of creating a new JSON one). As a bonus, they'd be localizable #338.


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Reply to this email directly or view it on GitHub:
https://github.com/w3c/manifest/issues/350