Support opening file/line references in an external editor from chat responses in github copilot

[EnoroF]

Support opening file/line references in an external editor from chat responses in github copilot

Description
When clicking file and line references returned in Copilot Chat responses, the current behavior opens the target inside VS Code.
Please add a configurable option to open the referenced file at the corresponding line in an external editor instead.

Expected behavior

Support configuring an external editor or external open handler.
Preserve file and line number navigation.
Keep the current VS Code internal open behavior as the default.
Use case
Some users want chat-generated file references to jump into another editor or toolchain instead of opening in the current VS Code window.