Error when trying to set a breakpoint in index.html

[rinselmann]

Describe the bug
When I try to set a breakpoint in a project that contains only an index.html file served from the filesystem, I get the following error: Error processing setBreakpoints: SyntaxError: Invalid regular expression

To Reproduce
Steps to reproduce the behavior:

1. Create new vscode project containing an index.html file with a script block
2. Create a launch configuration to open the index.html file using path
3. Start a debugging session
4. Try to set a breakpoint in index.html
5. See Error

VS Code Version: 1.56.2

Additional context
I believe this is due to urlToRegex incorrectly handling paths that are partially pre-escaped, which happens if the path ends with index.html. I have a fix that I'm planning on submitting a pull request for.