Exit if loading an invalid identity from disk (#2058)

* Exit if loading an invalid identity from disk

Previously, if an invalid identity was loaded from disk, ZeroTier would
generate a new identity & chug along and generate a brand new identity
as if nothing happened.  When running in containers, this introduces the
possibility for key matter loss; especially when running in containers
where the identity files are mounted in the container read only.  In
this case, ZT will continue chugging along with a brand new identity
with no possibility of recovering the private key.

ZeroTier should exit upon loading of invalid identity.public/identity.secret #2056

* add validation test for #2056

.github/workflows/report.sh

@@ -13,3 +13,9 @@ echo -e "\nBytes of memory definitely lost: $DEFINITELY_LOST"
 if [[ "$DEFINITELY_LOST" -gt 0 ]]; then
       exit 1
 fi
+
+EXIT_TEST_FAILED=$(cat *test-results/*summary.json | jq .exit_test_failed)
+
+if [[ "$EXIT_TEST_FAILED" -gt 0 ]]; then
+      exit 1
+fi