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
This commit renames the Netty 3 transport module from transport-netty to
transport-netty3. This is to make room for a Netty 4 transport module,
transport-netty4.
Relates #19439
