fix(PHP): Fixes PHP related deprecation notices & build bugs

[timnolte]

All Submissions:

• [x] Have you followed the plugin Contributing guideline?
• [x] Does your code follow the WordPress' coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

• Fixes #135
  • Fixes FILTER_SANITIZE_STRING deprecation notices using polyfill function.
• Fixes build related ignores and linting setup issues.
• Fixes the ability to generate a release dist regardless of the branch you are on.
• Fixes GitHub Actions workflows to ensure correct build environment setup and WP.org deployments.
• Adds feature/fix branch and develop code checks.
• Fixes #147
  • Fixes trim deprecation notices using newer Symfony/YAML package & null check before parsing YAML files.

How to test the changes in this Pull Request:

1. Checkout the PR.
2. Generate a build of the plugin. npm ci && npm run build
3. Generate a release of the plugin. npm run release
4. Copy the files in the dist directory to a WordPress installation.
5. Attempt to load WP-CFM bundles from the WP-CLI. wp config pull all
6. From the WordPress Dashboard ensure that creating bundles, saving bundles, pull/push bundles all function without errors or notices in the debug logs.

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you written new tests for your changes, as applicable?
• [x] Have you successfully run tests with your changes locally?

Changelog entry

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.

• Fixes FILTER_SANITIZE_STRING deprecation notices using polyfill function.
• Fixes trim deprecation notices using latest Symfony/YAML package & null check patch.

[timnolte]

@jgleisner & @tropicandid after some discussion with the Symfony devs with the issue I opened I was able to fix the trim() deprecation notice issue by adding in an appropriate check in the WP-CFM code without patching the package. Other than perhaps an outstanding issue with the new Devcontainer/Codespaces local development environment this should be good to go. I tested out the trim() issue using a version of the build on the WSWC site which was where I was seeing the issue being reported.