ci: add benchmark workflow for performance testing (#116)

Author: ttu

.github/workflows/benchmark.yml

@@ -0,0 +1,31 @@
+name: Benchmarks
+
+on:
+  workflow_dispatch:
+
+jobs:
+  benchmark:
+    runs-on: ubuntu-latest
+    env:
+      Solution_name: JsonFlatFileDataStore.sln
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: |
+            10.0.x
+      - name: Restore
+        run: dotnet restore
+      - name: Build
+        run: dotnet build -c Release
+      - name: Run Benchmarks
+        run: dotnet run --project JsonFlatFileDataStore.Benchmark/JsonFlatFileDataStore.Benchmark.csproj -c Release -- --filter '*'
+      - name: Upload Benchmark Results
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: benchmark-results
+          path: |
+            **/BenchmarkDotNet.Artifacts/**
+            BenchmarkDotNet.Artifacts/**
+          if-no-files-found: warn