4.x: WebClient HTTP 100-Continue

[tomas-langer]

For WebClient, we need to support this (esp. because of redirects when using streaming entity).

• io.helidon.nima.webclient.http1.HttpCallOutputStreamChain.ClientConnectionOutputStream#sendPrologueAndHeader
  • if we send expect continue, we need to do a timeout on read - and just send entity if response does not come
    this is needed for servers that do not support it, and where we would just hang indefinitely (or until timeout)

[Verdent]

Fixed by #7366