feat: support custom tool upload file

[hjlarry]

Summary

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

as OPENAPI doc, https://swagger.io/docs/specification/v3_0/describing-request-body/file-upload/
we can support file upload in custom tools.
some people require this feature: #9322

Screenshots

Before:	After:

Example YAML Schema:

openapi: 3.0.0
info:
  title: File Upload API
  version: 1.0.1
  description: API for uploading audio files for processing

servers:
  - url: https://ai.gitee.com/api/serverless

paths:
  /whisper-base/speech-to-text:
    post:
      summary: Upload and process file
      security:
        - BearerAuth: []
      requestBody:
        required: true
        content:
          audio/flac:
            schema:
              type: object
              properties:
                file:
                  type: string
                  format: binary
                  description: The audio file to be processed
              required:
                - file
      responses:
        '200':
          description: Successful response

Example JSON Schema:

{
  "openapi": "3.0.0",
  "info": {
    "title": "File Upload API",
    "version": "1.0.0",
    "description": "An API for uploading files with metadata"
  },
  "servers": [
    {
      "url": "https://httpbin.org"
    }
  ],
  "paths": {
    "/post": {
      "post": {
        "summary": "Upload a file",
        "description": "Upload a file with associated metadata",
        "operationId": "uploadFile",
        "requestBody": {
          "required": true,
          "content": {
            "multipart/form-data": {
              "schema": {
                "type": "object",
                "properties": {
                  "file": {
                    "type": "string",
                    "format": "binary",
                    "description": "The file to upload"
                  }
                }
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "Successful response"
          }
        }
      }
    }
  }
}

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods