Slight Tweaks to Slice Compiler Definitions

[InsertCreativityHere]

This PR renames 'arguments' to 'options' to match the terminology used by icerpc-csharp.
It also re-orders the anonymous types so that they are in the canonical order we always use:
Result, Sequence, Dictionary

[Copilot]

Pull request overview

Updates the Slice compiler definition schema to align terminology (“options”) with icerpc-csharp and to place anonymous types in the canonical order (Result, Sequence, Dictionary) across the Rust hand-mapped definitions and the Slice IDL.

Changes:

• Renamed args: Arguments to options: Options in the CodeGenerator interface and renamed the corresponding typealias.
• Reordered anonymous type definitions so ResultType appears before SequenceType and DictionaryType.
• Reordered the Symbol enum variants to the canonical order (including updating Rust explicit discriminant values).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
slicec/src/definition_types.rs	Reorders ResultType and updates Symbol variant ordering/IDs to match canonical anonymous type ordering.
slice/Compiler/SyntaxElements.slice	Reorders anonymous type struct declarations and updates doc wording to reflect canonical order.
slice/Compiler/CodeGenerator.slice	Renames generator “args” to “options” and reorders Symbol variants accordingly.

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[pepone]

What is the logic for this sorting?

[InsertCreativityHere]

I think it's loosely based on "similarity" and "language importance".

So, all the anonymous types should be next to one another, since they're conceptually similar. Same for all the user defined types. Typealias goes at the bottom because it's not similar to anything else, and is also the least important, and least useful of Slice constructs.

Then within each grouping, it's kind of just what feels right I guess. Sequence feels like it should come before Dictionary. Result should come before either of them because it has more in common with the user-defined types than it has with the collection types.

But this PR was just to make them consistent with the order we settled on them for slicec. If you have any other elements you want to swap around, feel free to comment!

Custom could be closer to TypeAlias, Enum could move beneath Struct, etc.