Dependencies API: `DELETE`

[khvn26]

Add DELETE /api/v1/environments/{environment_api_key}/features/{feature}/dependencies/{prerequisite_feature}.

DELETE:

• removes a correspodning rule.
• if the rule was the last one, removes the segment.

Acceptance criteria

• DELETE removes the rule for a given prerequisite feature.
• DELETE removes the segment if the rule for a given prerequisite feature was the last one.
• DELETE for a dependency arising from a user-authored segment is refused with a 400.
• V2 versioning environments get a published version.
• V1 versioning environments get a direct write.
• Both V2 and V1 versioned environments emit audit logs.
• Requires MANAGE_SEGMENT_OVERRIDES on the environment.
• A caller who can not write on the environment gets 404.