### Godot version

4.0.dev (61630d4e1e279278d29576b979b710b9025f473e)

### System information

Windows 10

### Issue description

> **Note**
> this issue was reported by @glimpsebeyond on [godot-vscode-plugin](https://github.com/godotengine/godot-vscode-plugin/issues/389#issuecomment-1302540744)

On Windows, due to a path separator mismatch (Godot: `/` and Windows: `\`), the debug adapter protocol fails as it thinks the opened project is in a different directory.

Likewise, there are other scenarios where this check is too strict, failing as well due to the drive letter's capitalization (`c:\` vs `C:\`. Good example from the linked issue:
```
[error] The editor and client are working on different paths; the client is on 
"d:\gameDev\gd4proj\builder\pawn.cs", but the editor is on "D:/gameDev/gd4proj/builder": CodeExpectedError: 
The editor and client are working on different paths; 
the client is on "d:\gameDev\gd4proj\builder\pawn.cs", but the editor is on "D:/gameDev/gd4proj/builder"
```

### Steps to reproduce

- Try using DAP from a project on Windows (like [VSCode's extension](https://github.com/godotengine/godot-vscode-plugin))

### Minimal reproduction project

N/A
Dictionary response = prepare_success_response(p_params), body;
	response["body"] = body;
	Dictionary args = p_params["arguments"];
	DAP::Source source;
	source.from_json(args["source"]);
	bool lines_at_one = DebugAdapterProtocol::get_singleton()->get_current_peer()->linesStartAt1;
	if (!is_valid_path(source.path)) {
		Dictionary variables;
		variables["clientPath"] = source.path;
		variables["editorPath"] = ProjectSettings::get_singleton()->get_resource_path();
		return prepare_error_response(p_params, DAP::ErrorType::WRONG_PATH, variables);
	}
	Array breakpoints = args["breakpoints"], lines;
	for (int i = 0; i < breakpoints.size(); i++) {
		DAP::SourceBreakpoint breakpoint;
		breakpoint.from_json(breakpoints[i]);
		lines.push_back(breakpoint.line + !lines_at_one);
	}
	Array updated_breakpoints = DebugAdapterProtocol::get_singleton()->update_breakpoints(source.path, lines);
	body["breakpoints"] = updated_breakpoints;
	return response;
}
Dictionary DebugAdapterParser::req_breakpointLocations(const Dictionary &p_params) const {