Delete package file API

What does this MR do?

This adds a new endpoint to the API to delete package files:

DELETE /projects/:id/packages/:package_id/package_files/:package_file_id

Screenshots (strongly suggested)

Deleting a package file:

→ curl --request DELETE -i --header "PRIVATE-TOKEN: $TOKEN" "http://gdk.test:3001/api/v4/projects/16/packages/3/package_files/3"
HTTP/1.1 204 No Content

When file does not exist:

→ curl --request DELETE --header "PRIVATE-TOKEN: $TOKEN" "http://gdk.test:3001/api/v4/projects/16/packages/1/package_files/1"
{"message":"404 Not Found"}

Without permissions to access project/package:

curl --header "PRIVATE-TOKEN: $TOKEN" "http://gdk.test:3001/api/v4/projects/16/packages/3/package_files/3"
{"error":"404 Not Found"}

Without authorization to delete file:

curl --header "PRIVATE-TOKEN: $TOKEN" "http://gdk.test:3001/api/v4/projects/16/packages/3/package_files/3"
{"error":"403 Forbidden"}

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
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Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related to #32107 (closed)