Fixes generating TypeSpec files

[waldekmastykarz]

Fixes generating TypeSpec files:

• adds sanitizing namespaces, and model- and operation names
• fixes handling null types
• fixes generating models from array items
• fixes sanitizing names when using language model

Thanks @tomorgan for reporting these issues and working with us to get them fixed!

[waldekmastykarz]

@dotnet-policy-service agree

[Copilot]

Pull Request Overview

This PR fixes issues in generating TypeSpec files by addressing namespace sanitization, model and operation naming, null type handling, and array item model generation.

• Added logic to merge model properties based on type and existence.
• Updated properties to allow mutations required for handling null types.
• Enhanced naming and sanitization flows in request log and language model components.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
dev-proxy-plugins/TypeSpec/TypeSpecExtensions.cs	Merges model properties with added handling for string literal "null".
dev-proxy-plugins/TypeSpec/Http.cs	Changes ModelProperty.Type from an init-only to a mutable property.
dev-proxy-plugins/RequestLogs/TypeSpecGeneratorPlugin.cs	Improves parameter and operation naming as well as array model generation.
dev-proxy-abstractions/LanguageModel/OllamaLanguageModelClient.cs	Updates logging messages for clearer output.

Comments suppressed due to low confidence (2)

dev-proxy-plugins/RequestLogs/TypeSpecGeneratorPlugin.cs:174

• Removing the MakeSingular call when constructing the BodyType for arrays may result in inconsistent naming; please verify that this change is intentional and consistent with other naming conventions used.

res.BodyType = "${rootModel.Name}[]";

dev-proxy-plugins/TypeSpec/TypeSpecExtensions.cs:25

• Comparing the property's Type to the literal "null" may lead to unexpected behavior if the string value is not intended; please verify that checking against "null" is intentional.

else if (existingProp.Type == "null")