fix(telemetry): resolve the node identity before the Application is built

resolveNodePublicKey() returned std::nullopt in three real cases: a first boot
with no wallet database, a standalone run (its wallet is a private temporary
database), and --newnodeid. Telemetry's resources are built during
ApplicationImp's member-init list and are immutable, so on those runs the node
reported an empty service.instance.id and no xrpl.node.id for the whole run,
while setup() minted a key moments later and patched only the tracer.

Replace it with resolveNodeIdentity(), which always returns a keypair: derived
from a configured seed, else read from an existing wallet database, else
minted. Main.cpp passes that pair to makeApplication(), ApplicationImp stores
it in nodeIdentity_ -- now declared before telemetry_ and no longer an optional,
because it is always set -- and builds the telemetry resource from it.

setup() calls getNodeIdentity(), which now persists rather than mints: it
stores the resolved pair when the wallet holds no identity, adopts the stored
one when it does, and clears first for --newnodeid. The write stays in setup()
because that is where the database exists; a standalone run has no persistent
wallet to write to, which is why the pair has to be decided before
construction rather than read back afterwards. Wallet gains storeNodeIdentity()
for that write, and getNodeIdentity(session) now uses it instead of repeating
the insert.

The three-argument makeApplication() mints a keypair, so jtx::Env and any other
test Application behave as a standalone run always did.

Also fold the three hand-rolled "meter from a NoopMeterProvider" copies into
telemetry::noopMeter(): the base-pointer call and the kMeterVersion argument are
both easy to get wrong alone, and the meter identity has to match the one the
histogram views select on.

The new gtest covers the wallet half: store-then-read, store not replacing an
existing identity, clear-then-store, and that the mint path persists. It adds
the tests.libxrpl > xrpl.rdb levelization edge, regenerated here.

.github/scripts/levelization/results/ordering.txt

@@ -196,6 +196,7 @@ tests.libxrpl > xrpl.nodestore
 tests.libxrpl > xrpl.peerfinder
 tests.libxrpl > xrpl.protocol
 tests.libxrpl > xrpl.protocol_autogen
+tests.libxrpl > xrpl.rdb
 tests.libxrpl > xrpl.resource
 tests.libxrpl > xrpl.server
 tests.libxrpl > xrpl.shamap