Add CI workflows to enhance the dev experience

[umbynos]

Add some checks workflows to this repo to enhance the developer experience and to catch common problems:

• https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/sync-labels.md
• https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-license.md
• https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-markdown-task.md
• https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-taskfiles.md

[umbynos]

#5 should unlock https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-license.md

[MatteoPologruto]

Sync-labels and the other checks added in the following PRs:

• sync-labels: Add CI workflow to synchronize with shared repository labels #3
• check-markdown-task: Add CI workflow to check Markdown files for problems #4
• check-license: Add CI workflow to check the license file #6
• check-taskfiles: Add CI workflow to validate Taskfiles #7

[umbynos]

Adding https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-shell-task.md should be beneficial too

[umbynos]

needs investigating on how to filter the shell files

[MatteoPologruto]

check-shell-task: #11