THRIFT-6170: Add a GitHub Actions CI job for the D library

Nothing in CI built or ran lib/d. build.yml had jobs for php, go,
java-kotlin, netstd, haxe, rust, python, nodejs, cpp and ruby, and its
shared CONFIG_ARGS_FOR_LIBS passed --without-d; docker.yml only builds
and validates the images. A regression in lib/d could only be found by
someone building D by hand, which is how THRIFT-6168 had to be verified.

Most of the pieces already existed: the docker images pin dmd 2.087.0
and the deimos header sets, configure.ac has AX_DMD and gates the
libevent and OpenSSL parts, and lib/d/Makefile.am already lists the
debug and release unittest binaries in TESTS. So the job installs dmd
the way the images do, bootstraps, configures with --with-d and the
other bindings off, and runs make -C lib/d check. The thrift compiler
artifact is needed because lib/d/test generates from .thrift sources.

Four things that are easy to get wrong here.

The deimos OpenSSL bindings are deliberately not installed. They are in
the docker images, but lib/d's OpenSSL modules do not link against the
OpenSSL 3.x that ubuntu-24.04 ships -- ERR_put_error was dropped in 3.0
and SSL_get_peer_certificate renamed to SSL_get1_peer_certificate, so
the first SSL unittest binary fails at link with two undefined
references. Leaving the headers out makes configure report "Building D
SSL tests: no", which drops those five modules from both the library and
the test set. This is a real lib/d gap rather than a CI one, filed as
THRIFT-6185; the step carries a comment saying to add the headers back
once that is closed. The libevent bindings are installed and their
modules are covered.

dmd is installed with apt rather than dpkg, because the deb depends on
libcurl4 and dpkg --install leaves the package unconfigured instead of
pulling it in.

The configure line matches --without-d with a word boundary.
Without it sed rewrites the first match in the argument list, which is
--without-dart, and the job would build Dart instead of D.

And the configure step checks that dmd was actually found. configure
disables a binding it cannot locate rather than failing, so without that
check a job whose toolchain step had quietly stopped working would keep
reporting success while running no tests at all, which is worse than
having no job.

Verified end to end on a clean ubuntu:24.04 with the job's own steps:
92 unittest binaries pass and 0 fail (43 modules in debug and release,
less the SSL ones), followed by lib/d/test's client_pool_test and
transport_test, both passing. With dmd removed the job fails at
configure rather than passing.

Client: d

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>