FE: Show Name/Description/Enabled/Preview components

Why are we doing this work

• Users want to use a Rule mode to create a scan execution policy because yaml can be hard to parse

Relevant links

Non-functional requirements

• Feature flag:
• Testing:

Implementation plan

• frontend abstract out name/description/enabled fields from scan_result_policy_editor.vue and put them in policy_editor_layout.vue to be reused by scan_execution_policy_editor.vue
• frontend create scan_execution_rule-mode feature flag

Verification steps

1. Navigate to a project with a GitLab Ultimate license and that has the :scan_execution_rule_mode feature flag turned on
2. Navigate to Security & Compliance => Policies => New policy => Scan Execution Policy
3. Verify rule mode works