Fixed a bug in ControlNet via API

[sunadarake]

Description

This PR is intended to fix the bug described in issue #110 .

Problem

File "D:\stable-diffusion-webui-forge\extensions-builtin\sd_forge_controlnet\scripts\controlnet.py", line 97, 
in get_enabled_units enabled_units = [x for x in units if x.enabled]

While accessing through the frontend, the args for ControlNet are a list of ControlNetUnit instances. However, when accessed through the API, it was a list of dict, causing an error.

Solution

For API access, convert args into ControlNetUnit instances. Additionally, handle cases where some keys in args are represented as tuples.

Moreover, since ControlNet uses images specified as base64-encoded data or image paths through the API, I added processing to convert the data to a format usable by ControlNet using lib_controlnet.utils.image_dict_from_any.

Screenshots/videos:

Checklist:

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

[huchenlei]

Duplicated. See #162.