co⚡e: Sparkplug™ MQTT edge

Made "GetMetricByx" return a valid pointer to GVL_sparkplug.InvalidRemoteMetric, so if anyone uses the result without proving it first, it doesn't cause an exception.

Exposed IRemoteMetric as PUBLIC (was INTERNAL)

Change some VAR_IN_OUTs to VAR_IN_OUT CONSTANT to allow calls like GetGroupId("G1") instead of GetGroupId(G1) where G1 : WSTRING := "G1";

v1.4.0.8 NBIRTHs received by PrimaryHost now allocates all the metrics with the right name

First pass at assigning remote metrics from NBIRTH

FB_RemoteMetric now contains two IStorageMetrics, so that the Payload can provide storage metrics for BIRTHS even when it has already given the metrics away to another MetricOwner.
One of these is registered with the Host._AllMetricsList, while the other is registered with the Host._MetricsPool, and will be later donated to a MetricOwner.

STweeped the source

Changed MetricStatus.ONLINE_OK to GOOD as that's what the sparkplug spec calls it

v1.4.0.7 Primary host now passes the NBIRTH to the Edge for further processing
Added a reason code (MetricStatus) to FB_RemoteMetric to indicate why the metric is stale

This featurebranch is ment to be the root for the PrimaryHost Feature.

Once the feauture has been completed it will either replace or be merged with the trunk