Improve MR Experience for Secure Scans on Non-Ultimate Plans - Create CE Security MR widget

Implementation Plan

• Add basic SecurityReportsApp component
• Dynamically import it into CE MrWidgetOptions, so it's not bundled (while not being used) in EE
• Call the Jobs API to determine whether any jobs have artifacts of type sast or secret_detection, and show/hide the widget accordingly
• Provide link to switch to pipelines tab to download artifacts
• Place behind core_security_mr_widget feature flag