[client-app] Add script that benchmarks new commits

Summary:
We want to setup the initial sync benchmark to run automatically with each
commit on a separate machine. This script does just that and dumps the
results to a directory. We can then have a separate script process them
and upload them to whichever service we want.

Test Plan: Run locally

Reviewers: evan, spang, juan

Reviewed By: juan

Differential Revision: https://phab.nylas.com/D4296

scripts/benchmark-new-commits.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+set -e
+
+function get_next_commit() {
+  local LAST_COMMIT=$1
+  local NEXT_COMMIT=$(git log master ^$LAST_COMMIT --ancestry-path --pretty=oneline | cut -d" " -f1 | tail -n 1)
+  echo "$NEXT_COMMIT"
+}
+
+BENCHMARK_RESULTS_DIR="$HOME/.benchmark_results"
+mkdir -p $BENCHMARK_RESULTS_DIR
+
+CWD="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+LAST_COMMIT=$(cat $BENCHMARK_RESULTS_DIR/last_commit)
+NEXT_COMMIT=$(get_next_commit $LAST_COMMIT)
+
+git checkout -q master
+git pull -q --rebase
+
+while [[ $NEXT_COMMIT != '' ]]
+do
+  echo $NEXT_COMMIT
+  git checkout -q $NEXT_COMMIT
+  bash $CWD/benchmark-initial-sync.sh > "$BENCHMARK_RESULTS_DIR/$NEXT_COMMIT-results.txt"
+  echo "$NEXT_COMMIT" > "$BENCHMARK_RESULTS_DIR/last_commit"
+  NEXT_COMMIT=$(get_next_commit $NEXT_COMMIT)
+done