Sort models per provider based on reasonable heuristics to avoid random default model

[felixarntz]

Fixes #117

This finally resolves a long-standing issue where the default model chosen for a provider would be sort of "random", or rather the first model returned by the provider's API listings.

The solution is to implement model sorting per provider via reasonable heuristics, without getting too opinionated:

• prefer flagship models (and then the common "lower/cheaper tier" variant, if applicable)
• prefer later versions
• prefer non-preview/non-experimental

Keep in mind that the sorting is per provider. There is no issue with this in terms of favoring any specific provider, the sorting is just for their models internally.

For easy testing of the sorted model IDs per provider, do this:

• Temporarily add a var_dump($modelId); for each $modelId iterated over in PromptBuilder::generateMapFromCandidates (e.g. line 1216).
• Use the built-in CLI tool, without specifying a model or model preference, but specifying --providerId (with each "anthropic", "google", "openai").

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[JasonTheAdams]

Oh wow! I was literally thinking through doing something like this as I was getting my day going this morning! Thanks for busting this out!

Just a couple comments/questions for the moment.

[JasonTheAdams]

This is great! I think it will really improve the default behavior for these Providers!