* Add parent-join module
This change adds a new module named `parent-join`.
The goal of this module is to provide a replacement for the `_parent` field but as a first step this change only moves the `has_child`, `has_parent` queries and the `children` aggregation to this module.
These queries and aggregations are no longer in core but they are deployed by default as a module.
Relates #20257
We kept `netty_3` as a fallback in the 5.x series but now that master
is 6.0 we don't need this or in other words all issues coming up with
netty 4 will be blockers for 6.0.
Today if the PreBuiltTransportClient is using Netty 4 transport, on
shutdown some Netty 4 threads could linger. This commit causes the
client to wait for these threads to shutdown upon termination.
This change does three things:
1. Makes PreBuiltTransportClientTests run since it was silently
failing on a missing dependency
2. Makes PreBuiltTransportClientTests pass
3. Removes the http.type and transport.type from being set in the
transport clients additional settings since these are set to `netty4` by
default anyway.
The `client/transport` project adds a new jar build project that
pulls in all dependencies and configures all required modules.
Preinstalled modules are:
* transport-netty
* lang-mustache
* reindex
* percolator
The `TransportClient` classes are still in core
while `TransportClient.Builder` has only a protected construcutor
such that users are redirected to use the new `TransportClientBuilder`
from the new jar.
Closes#19412
Jim Ferenczi
Simon Willnauer
Jason Tedor
Colin Goodheart-Smithe
Ryan Ernst