Add PHP language support to gitlab-advanced-sast

What does this MR do and why?

This MR adds configurable PHP file scanning support to gitlab-advanced-sast through a new input parameter ff_glas_enable_php_support.

Key changes:

• Added ff_glas_enable_php_support input (default: true) to control PHP scanning behavior
• When enabled: gitlab-advanced-sast scans PHP files, semgrep-sast excludes them
• When disabled: semgrep-sast continues to scan PHP files (backward compatible)
• Refactored template using !reference tags for better maintainability

Usage:

include:
 - component: gitlab.com/components/sast/sast@latest
   inputs:
     run_advanced_sast: true
     ff_glas_enable_php_support: false  # Optional: disable PHP scanning in Advanced SAST

References

https://gitlab.com/gitlab-org/gitlab/-/issues/523657+s

Manual QA

Before

• Project: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component
• Pipeline: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component/-/pipelines/1736011450

After ff_glas_enable_php_support: false

• Project: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component
• Pipeline: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component/-/pipelines/1833380752

After ff_glas_enable_php_support: true

• Project: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component
• Pipeline: https://gitlab.com/philipcunningham/manual-qa-glas-php-ci-component/-/pipelines/1833410544