feat: add support for dependency overrides (#44)

* feat: support overrides and required refactors

* update cli readme, include node flag and overrides

---------

Co-authored-by: Jon Church <[email protected]>

Author: wesleytodd

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 results
+perf/load/*/package-lock.json

README.md

@@ -22,6 +22,7 @@ We focus on **evaluation, not prescription**. Rather than dictating how to write
 - Tooling: [see Perf CLI Readme.md](./packages/cli/README.md)
 - Provide environments and tools to make measurements possible
 - Help contributors run performance tests and interpret results
+- Support dependency version overrides for testing performance across different Express versions
 - Maintain two categories of tests:
   - Focused unit benchmarks (in package repos)
   - E2E load tests of realistic applications (in express repo)