Augment the "Post install" dialog to allow reviewing the script

**Is your feature request related to a problem? Please describe.** The extension has integration with Swiftly that, if the user decides to install swiftly, will install the Swift toolchain version that are defined in the detected `.swift-version` file. However, some Swift toolchain installation has a post install script. The extension prompts the user if they script should be executed, but there is no way to review the contents of the script. <img width="263" height="427" alt="Image" src="https://github.com/user-attachments/assets/0eb1b424-de54-4678-b1ed-227b12c036de" /> **Describe the solution you'd like** As a developer, I would like to review the contents of the script that will be executed before granting access. **Describe alternatives you've considered** N/A **Additional context** N/A