feat: add more WebSocket options for subscription client

[hgiasac]

Add more WebSocket options that are supported natively by the nhooyr.io/websocket client such as HTTP header and compression.

// WebsocketOptions allows implementation agnostic configuration of the websocket client
type WebsocketOptions struct {
	// HTTPClient is used for the connection.
	// Its Transport must return writable bodies for WebSocket handshakes.
	// http.Transport does beginning with Go 1.12.
	HTTPClient *http.Client

	// HTTPHeader specifies the HTTP headers included in the handshake request.
	HTTPHeader http.Header

	// Host optionally overrides the Host HTTP header to send. If empty, the value
	// of URL.Host will be used.
	Host string

	// CompressionMode controls the compression mode.
	// Defaults to CompressionDisabled.
	//
	// See docs on CompressionMode for details.
	CompressionMode websocket.CompressionMode

	// CompressionThreshold controls the minimum size of a message before compression is applied.
	//
	// Defaults to 512 bytes for CompressionNoContextTakeover and 128 bytes
	// for CompressionContextTakeover.
	CompressionThreshold int
}

It's useful for GraphQL servers that validate custom auth tokens on the header.

client := graphql.NewSubscriptionClient(serverEndpoint).
    WithWebSocketOptions(graphql.WebsocketOptions{
        HTTPHeader: http.Header{
            "Authorization": []string{"Bearer random-secret"},
        },
    })

[github-actions]

Package	Line Rate	Health
github.com/hasura/go-graphql-client	71%	➖
github.com/hasura/go-graphql-client/ident	100%	✔
github.com/hasura/go-graphql-client/pkg/jsonutil	84%	✔
Summary	75% (1414 / 1883)	➖

Minimum allowed line rate is 60%