[DEV-787] Dynamic value mapper for event metadata #81

Job	Run time
build / Build (8)	1m 10s
build / Build (17)	1m 11s
build / Build (11)	1m 17s
Tests (CI) / load_configuration / load	2s
Tests (CI) / Secure (Streams)	1m 47s
Tests (CI) / Secure (PersistentSubscriptions)	2m 4s
Tests (CI) / Single node (Telemetry)	1m 36s
Tests (CI) / Cluster (PersistentSubscriptions)	1m 56s
Tests (CI) / Single node (PersistentSubscriptions)	1m 57s
Tests (CI) / Single node (MultiStreamAppend)	1m 38s
Tests (CI) / Single node (Streams)	1m 37s
Tests (CI) / Cluster (MultiStreamAppend)	1m 46s
Tests (CI) / Cluster (Streams)	2m 17s
	20m 18s

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