Add inline YAML prompt override debug setting

[dileepyavan]

Summary

• add an advanced debug setting for providing prompt override YAML directly in configuration. github.copilot.chat.debug.promptOverrideString
• support applying prompt overrides from either inline YAML or a file, preferring the inline value when both are set
• add tests for the new configuration key and the inline prompt override behavior

example: "github.copilot.chat.debug.promptOverrideString": "systemPrompt: "You are a concise coding assistant. Always explain tool choices briefly."\ntoolDescriptions:\n read_file:\n description: "Read a file from the workspace when exact file content is needed."\n grep_search:\n description: "Search the workspace for exact text or regex matches before reading files.""

[Copilot]

Pull request overview

Adds a new advanced debug configuration option to override the agent prompt/tool YAML inline (in settings) as an alternative to providing a YAML file, and wires this into the tool-calling loop so inline overrides take precedence when both are set.

Changes:

• Introduces chat.debug.promptOverrideString config key and contributes it to package.json advanced settings.
• Updates prompt override application to support inline YAML or a YAML file (preferring inline when both exist).
• Adds unit tests covering the new configuration key and inline override behavior.

Show a summary per file

File	Description
src/platform/configuration/common/configurationService.ts	Adds ConfigKey.Advanced.DebugPromptOverrideString to configuration keys.
package.json	Contributes the new github.copilot.chat.debug.promptOverrideString setting to the advanced configuration section.
src/extension/intents/node/toolCallingLoop.ts	Applies configured prompt overrides using either inline YAML or a file during prompt construction.
src/extension/intents/node/promptOverride.ts	Implements inline YAML parsing/application and a unified “configured overrides” entry point.
src/extension/intents/node/test/promptOverride.spec.ts	Adds tests for inline overrides and inline-vs-file precedence.
src/extension/test/node/configurations.spec.ts	Adds a test asserting the new setting key is camelCase and present in the advanced section.

Copilot's findings

• Files reviewed: 6/6 changed files
• Comments generated: 2

[rwoll]

🚀 it!

[dileepyavan]

Closing this as copilot repo changed. Opened PR on vscode repo: microsoft/vscode#308309