Update Stream interfaces diagrams

[blake-regalia]

Currently these diagrams show | RegExp for some of the arguments which is from an older version.

[elf-pavlik]

We could use Mermaid: Class Diagram to have easily editable source

classDiagram
  class EventEmitter
  class Stream {
    +read() Quad
  }
  EventEmitter <|-- Stream : Extends
  class Source {
    +match(subject: Term, predicate: Term, object: Term, graph: Term) Stream
  }
  class Sink {
    +import(stream: Stream) EventEmitter
  }
  class Store {
    +remove(stream: Stream) EventEmitter
    +removeMatches(subject: Term, predicate: Term, object: Term, graph: Term) EventEmitter
    +deleteGraph(graph: Term) EventEmitter
  }
  Source <|-- Store: Extends
  Sink <|-- Store : Extends

Preview above in live editor

In another repo I have setup to auto render image using github action.