Make protocol URL configurable for editor integration in openFile

Currently, the openFile function (in packages/react-grab/src/primitives.ts) uses a hardcoded protocol URL to open files in editors, such as vscode://file/.... This limits flexibility for users who may use different flavors or versions of editors (e.g., vscode-insiders://file/..., or other editor protocols).

**Feature request:**

Allow users to customize or control the protocol URL used to open files. This could be via a configuration option, environment variable, or function parameter.

**Benefits:**

- Supports more user setups (e.g., VSCode Insiders, other editors with protocol support)
- Improves developer experience for teams with mixed editor environments
- Enables easier testing and extension for future integrations

**Proposal:**

- Abstract the protocol part of the URL in openFile and related helpers.
- Provide a way (parameter, config, env) to override the protocol.
- Update documentation to describe how users can change the protocol.