Only validate package.json files in specified paths

The project infrastructure validates the package.json npm configuration files against their JSON schema.

Previously, in order to provide validation coverage for all package.json files in any locations in the repository, a
"globstar" was used to cause the validator to recursively search the entire file tree under the repository. That
approach is problematic because the repository contains externally maintained files (e.g., the npm packages under the
node_modules folder). Searching and validating these files is inefficient at best and the cause of spurious failures at
worst.

This is avoided by targeting the search. Support for a repository maintainer to configure any number of specific
locations of npm-managed projects in the "Check npm" workflow has been added, so this system is used to target the
validations. When the `npm:validate` task is ran by a contributor on their local clone, it defaults to the root of the
repository, but the path can be configured by setting the PROJECT_PATH taskfile variable via an argument to the task
invocation command.

Author: per1234

.github/workflows/check-npm-task.yml

@@ -30,8 +30,15 @@ permissions:
 
 jobs:
   validate:
+    name: validate (${{ matrix.project.path }})
     runs-on: ubuntu-latest
 
+    strategy:
+      fail-fast: false
+      matrix:
+        project:
+          - path: .
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -48,7 +55,11 @@ jobs:
           version: 3.x
 
       - name: Validate package.json
-        run: task --silent npm:validate
+        run: |
+          task \
+            --silent \
+            npm:validate \
+            PROJECT_PATH="${{ matrix.project.path }}"
 
   check-sync:
     name: check-sync (${{ matrix.project.path }})

Taskfile.yml

@@ -252,7 +252,10 @@ tasks:
 
   # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-npm-task/Taskfile.yml
   npm:validate:
-    desc: Validate npm configuration files against their JSON schema
+    desc: |
+      Validate npm configuration files against their JSON schema.
+      Environment variable parameters:
+      PROJECT_PATH: Path of the npm-managed project (default: {{.DEFAULT_NPM_PROJECT_PATH}}).
     vars:
       # Source: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/package.json
       SCHEMA_URL: https://json.schemastore.org/package.json
@@ -294,7 +297,8 @@ tasks:
       STYLELINTRC_SCHEMA_URL: https://json.schemastore.org/stylelintrc.json
       STYLELINTRC_SCHEMA_PATH:
         sh: task utility:mktemp-file TEMPLATE="stylelintrc-schema-XXXXXXXXXX.json"
-      INSTANCE_PATH: "package.json"
+      INSTANCE_PATH: >-
+        {{default .DEFAULT_NPM_PROJECT_PATH .PROJECT_PATH}}/package.json
       PROJECT_FOLDER:
         sh: pwd
       WORKING_FOLDER: