fix standalone compilation of `trusted_node_sync.nim` (#5861)

#5544 contained a regression that broke standalone compilation of
`trusted_node_sync` as a main module. Fix it, and add to CI.

.github/workflows/ci.yml

@@ -221,6 +221,11 @@ jobs:
         run: |
           make -j nimbus_beacon_node LOG_LEVEL=TRACE NIMFLAGS="-d:has_deposit_root_checks=1"
 
+      - name: Build files with isMainModule
+        run: |
+          source env.sh
+          nim c beacon_chain/trusted_node_sync
+
   lint:
     name: "Lint"
     runs-on: ubuntu-latest

beacon_chain/trusted_node_sync.nim

@@ -540,16 +540,18 @@ proc doTrustedNodeSync*(
 
 when isMainModule:
   import
-    std/[os],
+    std/os,
     networking/network_metadata
 
   let
+    cfg = getRuntimeConfig(some os.paramStr(1))
+    databaseDir = os.paramStr(2)
     syncTarget = TrustedNodeSyncTarget(
       kind: TrustedNodeSyncKind.StateId,
       stateId: os.paramStr(5))
     backfill = os.paramCount() > 5 and os.paramStr(6) == "true"
     db = BeaconChainDB.new(databaseDir, cfg, inMemory = false)
   waitFor db.doTrustedNodeSync(
-    getRuntimeConfig(some os.paramStr(1)), os.paramStr(2), os.paramStr(3),
+    cfg, databaseDir, os.paramStr(3),
     os.paramStr(4), syncTarget, backfill, false, true)
   db.close()