Bug/Feat: Sandbox config to selectively enable tools

### Describe the feature or problem you'd like to solve

Feature Request: Sandbox config in settings.json to selectively enable tools, and/or whitelist bundled copilot package tools

### Proposed solution

potentially have some tools { ... } within sandbox section in settings.json to enable allowed tools/apps/executables
_(or provide documentation on how best to accomplish this if fits somehow in current schema)_

more specifically, encountered this around copilot bundled rg ripgrep, while in sandbox enabled:
```
Search "xunit\.V3" (sandboxed) sh: 1:~/.copilot/pkg/linux-x64/1.0.75/ripgrep/bin/linux-x64/rg: not found

Search is blocked because the bundled  rg  executable is unavailable under the current sandbox policy.
Please review  /sandbox  and retry.
```

ideally specifically around this, executable packages that are bundled within distributed copilot are just marked "safe" by default and end user does not need to do anything additional to whitelist to allow these in sandbox mode

### Example prompts or workflows

_No response_

### Additional context

_No response_

Empieza leyendo la configuración settings.json y el comportamiento de la política /sandbox; después, sigue cómo se comprueba el ejecutable incluido en ~/.copilot/pkg/linux-x64/1.0.75/ripgrep/bin/linux-x64/rg. Determina si el esquema existente puede expresar herramientas permitidas o si las herramientas incluidas necesitan un valor predeterminado seguro; se considera completado cuando la configuración o documentación prevista esté definida y sandboxed Search pueda usar rg.

Escrito por el modelo de indexación a partir del texto del issue.