Add diagnostics

[CopyDemon]

Fixes
Fix the UI panel layout, remove the variables panel, and change that panel to a multi-task panel. Now it can display diagnostics.

Proposed changes:
Create a diagnostics panel to display diagnostics.

Notice
Now the diagnostics only run on fixed JSON data, later when the API is up to date, will rewrite some functions in diagnostics.

Legal Acknowledgement

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1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
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[dangunter]

I assume this will be incorporated in a future PR that uses real/live diagnostic info. Should we move this PR back to draft?

[CopyDemon]

@dangunter you are right, I just turned this PR into a draft, and start to work on serving the new UI with FastAPI and do some mockups for diagnostics. Once the API part is cleaned up and UI is approved, I can come back and update the UI template in code. if need some tests I still can use the old diagnostics UI template in this PR.

For now

[lbianchi-lbl]

The current plan is to merge #43 first and then this one (which is also expected to resolve the current CI failures).

[lbianchi-lbl]

Suggested change

	match request.function_name:
	case "display_underconstrained_set":
	dt.display_underconstrained_set(stream=output_stream)
	case "display_constraints_with_large_residuals":
	dt.display_constraints_with_large_residuals(stream=output_stream)
	case "display_potential_evaluation_errors":
	dt.display_potential_evaluation_errors(stream=output_stream)
	func = getattr(dt, request.function_name, None)
	if func is None:
	...
	# TODO handle error
	func(stream=output_stream)

[dangunter]

@CopyDemon Could you rebase this on main? I see some merge conflicts there

[CopyDemon]

Could you rebase this on main? I see some merge conflicts there

Working on it now