fix: app icon in app_dsl_service.py

[ZuzooVn]

Checklist:

Important

Please review the checklist below before submitting your pull request.

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

Description

• Add icon_type
• Fix hardcode emoji feat: custom app icon #7196

Type of Change

• Bug fix (non-breaking change which fixes an issue)

[crazywoola]

@xuzuodong Please take a look at this as well.

[xuzuodong]

This was done intentionally by me during the development of #7196. The exported DSL file might be imported into other distributions, for example, a DSL file exported in cloud.dify.ai might be imported into a user’s self-deployed version of Dify. In such cases, the imported images will be invalid.