CI Improvements

1. Use newer node.js 18.16.0
2. Use Azure Pipelines cache@2 for faster npm installations
3. Compute ESY_BASH_VERSION variable for pipeline releases

.ci/esy-build-steps.yml

@@ -1,9 +1,23 @@
+---
 # Cross-platform set of build steps for building esy projects
 
 steps:
   - task: NodeTool@0
     inputs:
-      versionSpec: '8.9'
+      versionSpec: '18.16.0'
+  - bash: |
+      NPM_CACHE_DIR=$(npm config get cache)
+      ESY_BASH_VERSION=$(node -e 'console.log(require("./package.json").version)')
+      echo "##vso[task.setvariable variable=NPM_CACHE_DIR]$NPM_CACHE_DIR"
+      echo "##vso[task.setvariable variable=ESY_BASH_VERSION]$ESY_BASH_VERSION"
+    displayName: Compute pipeline variables
+  - task: Cache@2
+    inputs:
+      key: 'npm | "$(Build.SourcesDirectory)/package-lock.json"'
+      restoreKeys: |
+         npm
+      path: $(NPM_CACHE_DIR)
+    displayName: Cache NPM
   - script: npm i -g esy
   - script: npm install
   - script: npm run build-exe
@@ -19,8 +33,8 @@ steps:
   - task: PublishBuildArtifacts@1
     displayName: 'Release Package'
     inputs:
-        PathtoPublish: './esy-bash-0.3.20.tgz'
-        ArtifactName: npm-package
+        PathtoPublish: './esy-bash-$(ESY_BASH_VERSION).tgz'
+        ArtifactName: esy-bash-$(ESY_BASH_VERSION)
   - script: node postinstall.js
     displayName: "node postinstall.js (iteration 1)"
   - script: npm run test