Rewrite to use node:http instead of express, and more options

[KraXen72]

Hi, i stumbled upon your adapter for IIS, and while it was a good start, it was not working that well for me. I modified it pretty extensively, adding features i needed. I thought it might be a good idea to contribute them back, since you said contributions are welcome in the readme.

Differences

• use node:http server instead of express, so it does not require an external dependency of express
• add environment variables to web.config, to pass to iisnode. Gets POST requests, form actions to work, instead of throwing error 403
• getClientAddress now works again, using the x-forwarded-for header and iisnode's enableXFF="true"
• added outputWhitelist option: a whitelist array to not be deleted from .svelte-kit/adapter-iis during build (explained in readme)
• added externalRoutes option: allow some routes to be not rewritten to sveltekit, for example, for Virtual Directories support
• added externalRoutesIgnoreCase option: controls case sensitiveness of these routes
• added healthcheckRoute option: a simple /healthcheck route for debuging while setting up IIS
• rewrote the readme pretty extensibly, including a troubleshooting section for people who aren't that familiar with IIS.
• better types for the options, extended adapter-node's option interface

The biggest switch is from using express to node:http. While they aren't completely the same, it has worked for all my use-cases, and i haven't noticed any differences. My motivation behind the switch is:

• unless the app has runtime dependencies, you shouldn't npm/yarn/pnpm install on the build output, and rather use devDependencies, which if imported, are packaged. Introducing a runtime dependency unnecessarily complicates the build & update process.
• adding the external dependency of express and installing it there or globally is really cumbersome and adds friction

Please let me know any requested changes.

[abaga129]

@KraXen72 Sorry I didnt see your PR sooner. This all looks great. I'm going to look everything over and test it a bit but I dont see any reason not to merge this as it seems to be a major improvement!

[KraXen72]

thanks for merging! i'll likely contribute some more stuff in the future :3

[abaga129]

That sounds great! Thank you for this big contribution. I went ahead and squashed the commits into a single commit just to clean up the git history. I hope that's okay. So you will need to updated your fork before making another PR.

I'm glad to see we can work together on IIS support for Sveltekit!

[abaga129]

Also @KraXen72 I've tagged v1.1.0 so you should be able to install it from the npm registry now

[KraXen72]

sure, great!