[Beta] Add Shim Performance Testing (#1302)

* Add shim performance tests.

* Update package-lock.json

* Fix sample env.

.gitignore

@@ -38,3 +38,5 @@ undefined/temp/appInsights-node/applicationinsights.log
 test/certs/server-key.pem
 # Ignore folder created during test runs
 undefined/*
+node_modules
+dist-esm

test/performanceTests/README.md

@@ -0,0 +1,10 @@
+### Guide
+
+1. Copy the `sample.env` file and name it as `.env`.
+2. Create an Application Insights resource and populate the `.env` file with connectionString.
+3. Run the tests as follows (parameters can be modified to as appropriate):
+
+- Tracking Dependencies (spans)
+  - `npm run perf-test:node -- TrackDependencyTest --warmup 1 --iterations 1 --parallel 2 --duration 15`
+- Tracking Traces (logs)
+  - `npm run perf-test:node -- TrackTraceTest --warmup 1 --iterations 1 --parallel 2 --duration 15`