FE: Update UI Policy Editor to allow to include CI code block or path

Why are we doing this work

In scope of this issue we would like to add ability in UI Policy Editor to include Custom YAML block according to designs. In scope of this issue specifically we want to allow users to add new Action type to Scan Execution Policy with ability to select Running Inserted CI Code Block or Linked existing CI file.

This feature should be implemented behind the feature flag, so we can easily enable and disable it and should use the YAML structure:

actions:
- type: custom
  ci_configuration: |-
    test2:
      stage: test
      script:
      - echo "This is a test included from security policy"

Relevant links

• Designs
• Epic

Non-functional requirements

• Documentation:
• Feature flag: this feature should be implemented behind feature flag
• Performance:
• Testing:

Implementation plan

• frontend implement !136587 (comment 1649799039)

Verification steps

TBD