fix(windows): nsis failed to resolve resources with `$` in their name. closes #9657

[enkhjile]

Registering a global escape function that replaces $ with $$ in Handlebars causes the build step to fail when resources contain $ in their names, because NSIS commands like File /a cannot resolve the escaped paths. #9657

I've added a helper that unescapes $$ back to $ and modified the corresponding resource expression in installer.nsi to use this helper.

If there are better solutions, I'd be happy to implement them.