rework set_named_arg

[w-e-w]

• extracted from Another hr button fix  #14728

change identifying a script from using Scripts class name to Scripts internal name an as not all Script have unique names

raise RuntimeError when there's issue

reason the identifying a script using class name is problematic as currently as there's no convention to using unique names with there Script class name
in base webui alone we have multiple scripts that are all called Scripts
not to mention lots of extensions use the same Script name for the Script

hence the change to using the scrip internal name

using == to match elem_id

• and as opposed to returning none when there is an issue like script or element id is not found, raise runtime error

• even though comparing the element ID using in is convenient as it allows you to ignore stuff like the prefix txt2img_ in txt2img_seed but this would cause a potential issue in that depending on the order of your arg
  for example if you have two elements args with IDs of seed and subseed
  if the order of the args is ['seed', 'subseed'] then everything function as normal
  but if the order is ['subseed', 'seed'] when matching for seed it be match with subseed
  hence changed to using ==

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

[AUTOMATIC1111]

The reason for in instead of == was to be able to use the same name for both img2img and txt2img.

[w-e-w]

I forgot to copy the reasoning behind using == for the last PR

tldr is that using in is more flexible but it's also broken

unless you want to add extra logic like if no match if found with == the try matching with in

---

the tab prefix issue is also in part why I wanted to add update_script_args as even though it's harder to maintain
it is more explicit in its functionality

[w-e-w]

we can add an argument fuzzy
set_named_arg(self, args, script_name, arg_elem_id, value, fuzzy=False)
something like if fuzzy use in else ==

[AUTOMATIC1111]

Yeah, let's do that.

[w-e-w]

done