Improve Install location error message in EXE installer

### Checklist

- [x] I added a descriptive title
- [x] I searched open requests and couldn't find a duplicate

### What is the idea?

There is an an error message displayed currently when user tried to provide invalid special characters in the Installation directory path. This error message needs to be more clear/descriptive than its current state. If there are multiple invalid characters, current message shows only first invalid character.

### Why is this needed?

This would benefit the customer to understand the error easily and hence they will fix the issue quickly from their end. They will be able to remove all invalid characters fast and proceed with correct installation steps.

### What should happen?

For example, when user provides %^ characters, the error message should say: Error 'Destination folder' contains the following invalid character(s): %^

### Additional Context

_No response_

No source file, test, or entry point is named in the issue. Start by locating the EXE install-directory validation entry point and reproducing the invalid-character case; done means the error message identifies every invalid character and the installation remains blocked until the path is corrected.

Written by the indexing model from the issue text.