Update NamedMojoIpcServer to support CRD usages of MojoIpcz

This CL makes the following changes:

1. Introduce `extra_send_invitation_flags` in the EndpointOptions
   struct, since the CRD server process is at a lower security level
   than its clients so `MOJO_SEND_INVITATION_FLAG_ELEVATED` needs to
   be set.
2. Remove the return state when the server fails to open the client
   process. With MojoIpcz, the server can make a connection/send an
   invitation with an invalid process handle, as long as the client has
   a valid process handle to the server, which is the case for CRD.

Bug: 1378803
Change-Id: Ifec79e71d1314bbebf60e400df7ab925d2bd6e43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4457494
Auto-Submit: Yuwei Huang <yuweih@chromium.org>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Noah Rose Ledesma <noahrose@google.com>
Reviewed-by: Noah Rose Ledesma <noahrose@google.com>
Cr-Commit-Position: refs/heads/main@{#1133783}