feat: pom extractor

Signed-off-by: Umberto Sgueglia <usgueglia@contractor.linuxfoundation.org>

Author: ulemons

backend/.env.dist.local

@@ -199,3 +199,10 @@ OSV_ECOSYSTEMS=npm,Maven
 OSV_TMP_DIR=/tmp/osv
 OSV_BATCH_SIZE=500
 OSV_DERIVE_BATCH_SIZE=1000
+# pom-fetcher non-critical (DB-only)
+POM_FETCHER_NON_CRITICAL_BATCH_SIZE=500
+POM_FETCHER_NON_CRITICAL_CONCURRENCY=20
+
+# pom-fetcher critical (HTTP)
+POM_FETCHER_BATCH_SIZE=100
+POM_FETCHER_CONCURRENCY=5