The API add a function to generate a task_id

[cklogic]

Description

• Add the generate_task_id function to support generating task_id according to stable-diffusion-webui rules through the interface, instead of letting the caller randomly generate force_task_id and pass it to txt2img and img2img

Screenshots/videos:

Checklist:

• [x] I have read contributing wiki page
• [x] I have performed a self-review of my own code
• [x] My code follows the style guidelines
• [x] My code passes tests

[AUTOMATIC1111]

Why?

[cklogic]

Why?

1. If the API has a task_id generation interface, the caller does not need to develop and maintain a unique task_id generator.

2. Or, when calling the txt2img api, return the task_id immediately and then execute it asynchronously.

[light-and-ray]

To generate random string you don't need to use an online service - you can do it locally! 😄

[AUTOMATIC1111]

just like light-and-ray says, generate task id clientside

[AUTOMATIC1111]

reopen if there's more