cli: add sideEffects: false to plugin templates

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/tall-countries-float.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Add `"sideEffects": false` to `package.json` in frontend package templates. This can be added to existing packages using the new `yarn fix` command.

packages/cli/templates/default-common-plugin-package/package.json.hbs

@@ -20,6 +20,7 @@
   "backstage": {
     "role": "common-library"
   },
+  "sideEffects": false,
   "scripts": {
     "build": "backstage-cli package build",
     "lint": "backstage-cli package lint",

packages/cli/templates/default-plugin/package.json.hbs

@@ -18,6 +18,7 @@
   "backstage": {
     "role": "frontend-plugin"
   },
+  "sideEffects": false,
   "scripts": {
     "start": "backstage-cli package start",
     "build": "backstage-cli package build",

packages/cli/templates/default-react-plugin-package/package.json.hbs

@@ -19,6 +19,7 @@
   "backstage": {
     "role": "web-library"
   },
+  "sideEffects": false,
   "scripts": {
     "start": "backstage-cli package start",
     "build": "backstage-cli package build",

packages/cli/templates/web-library-package/package.json.hbs

@@ -18,6 +18,7 @@
   "backstage": {
     "role": "web-library"
   },
+  "sideEffects": false,
   "scripts": {
     "start": "backstage-cli package start",
     "build": "backstage-cli package build",