fix(TypeScript): use import type for enum types

[kwestground]

Summary

Enums are generated as TypeScript type aliases (export type MyEnum = ...),
so they must use import type for compatibility with verbatimModuleSyntax.

Problem

When using verbatimModuleSyntax: true (recommended for modern TypeScript projects),
the generated client fails at runtime with:

The requested module does not provide an export named 'MyEnum'

This is because enum types are imported without the type prefix.

Solution

Added check for CodeEnum in GetShouldUseTypeImport() method.

Related Issues

Fixes part of #2959

Reproduction Repository

Minimal reproduction: https://github.com/kwestground/kiota-enum-repro

git clone https://github.com/kwestground/kiota-enum-repro
cd kiota-enum-repro
npm install
npm run generate   # Generate with official Kiota
npm run build      # See TS1484 error

Checklist

• Added unit test WritesImportTypeStatementForEnum
• All existing tests pass

[kwestground]

@microsoft-github-policy-service agree

[Copilot]

Pull request overview

This PR fixes a critical issue where TypeScript enum imports fail at runtime when using verbatimModuleSyntax: true by ensuring enum types use import type syntax.

Changes:

• Added check for CodeEnum in GetShouldUseTypeImport() method to return true for enum types
• Added comprehensive unit test WritesImportTypeStatementForEnum following existing test patterns

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Kiota.Builder/Writers/TypeScript/CodeUsingWriter.cs	Added CodeEnum check in GetShouldUseTypeImport() to ensure enums use import type syntax, with explanatory comments referencing the issue
tests/Kiota.Builder.Tests/Writers/TypeScript/CodeUsingWriterTests.cs	Added test WritesImportTypeStatementForEnum that verifies enums generate import type statements, following the same pattern as existing tests for interfaces and models

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[baywet]

Thanks for the contribution!
Can you please also add a changelog entry? (unreleased, changed)

[baywet]

Thank you for making the changes!