Remove extra lockfiles and gitignore them to prevent accidental commits.

Author: nellh

.gitignore

@@ -13,3 +13,7 @@ dist/
 *.egg-info/
 bids-validator-web/out/
 bids-validator-web/.next/
+
+# Only use global yarn.lock
+bids-validator/yarn.lock
+bids-validator-web/yarn.lock