perf(webpack-cli): cache schema arguments and use map lookups for options (#4760)

Author: alexander-akait

.changeset/fast-pumas-cache.md

@@ -0,0 +1,5 @@
+---
+"webpack-cli": patch
+---
+
+Reduced CLI startup CPU and memory usage by caching schema-derived argument metadata, registering only the options present in the arguments, and reading config directories once during default-config discovery.