Adopting HTTP QUERY method

[elf-pavlik]

This is follow up to the short discussion during the call. HTTP QUERY is a PR https://www.rfc-editor.org/info/rfc10008/ and people are implementing it. It was brought up to Solid CG over a year ago by @CxRes

• QUERY for fetching auxiliary resources solid/specification#724

Now @ebremer created a PR using it for Type Index/Search

• Replace GET/POST with new HTTP QUERY RFC10008 #179

We are discussing using it for notifications

• feat(notifications): Add WebSocket and Server-Sent Event channels #162
• LWS Notifications Feature #103
• @CxRes IETF presentation https://youtu.be/kleBCv02n9I?t=1308

@CxRes also suggested it in

• Abstract 'containers' as Link Set representations of arbitrary relational metadata #116 (comment)

@ebremer also mentioned drafting something for SPARQL and I would be interested if we can use it for https://linkeddatafragments.org/ in general.

[TallTed]

The method QUERY (RFC 10008) is obviously an update of HTTP/1.1 and/or HTTP/2.0, but it doesn't say that it updates those RFCs. There are many updates required across many IETF documents (or at least pages that discuss those documents). See #179 (comment) for more.