[chore] Update Windows signing Cert

[davegarthsimpson]

Motivation

We need to update our windows signing cert.

Change description

Now that our signing is hardware dependent we have no choice other than to move our windows build process to a self hosted runner. This way we can use custom signing logic together with electron-builder.

This PR:

• avoids installing anything during the build job on windows, the self hosted runner has everything persistently preinstalled;
• updates workflow file variables to point to our new certificate;
• moves our windows build process to a self hosted runner;
• adds a custom javascript script. electron-builder now delegates signing on windows to this script.

Other information

arduino/arduino-create-agent#950
arduino/arduino-cli#2599

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)