ci: migrate to npm trusted publishing

[just-jeb]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[x] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

CI uses NPM_TOKEN secret for publishing packages to npm. Classic tokens have been revoked by npm and granular tokens expire every 90 days.

Issue Number: N/A

What is the new behavior?

Uses npm Trusted Publishing with OpenID Connect (OIDC) - no tokens needed, more secure.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Prerequisites before merging:
Set up Trusted Publisher on npm for each package at https://www.npmjs.com/package/@angular-builders/<pkg>/access:

• Workflow: ci.yml
• Organization: just-jeb
• Repository: angular-builders

After merging, the NPM_TOKEN secret can be deleted from GitHub.