Remove Slice1 and compilation mode from Compiler definitions

[bernardnormier]

No description provided.

[Copilot]

Pull request overview

This pull request removes Slice1-specific language constructs from the compiler's internal representation. The changes simplify the compiler's data model by eliminating support for deprecated Slice1 features (classes, exceptions, and compilation modes) while maintaining support for Slice1 files in the actual codebase (Ice/ and IceRpc/ directories use mode = Slice1).

Changes:

• Removed Class and Exception struct definitions from the compiler's internal AST representation
• Removed CompilationMode enum and associated metadata tracking
• Removed exception-related documentation metadata (ThrowsTag and throws field)

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
Compiler/SyntaxElements.slice	Removed Class and Exception structs, isSlice1Only field from Struct, and exceptionSpecification from Operation; reordered fields in Interface, Operation, and Enum
Compiler/DocComment.slice	Removed ThrowsTag struct and throws field from DocComment to eliminate exception documentation metadata
Compiler/CodeGenerator.slice	Removed CompilationMode enum, compilationMode field from SliceFile, and Class/Exception variants from Definition enum

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[bernardnormier]

I think it's more logical to put idempotent toward to front, like in the Slice syntax.

[InsertCreativityHere]

The changes look good to me!

But I am still on the fence about the implications of removing mode = Slice1 in favor of slice2cs --icerpc though.