in_windows_exporter_metrics: add IIS collector

**Is your feature request related to a problem? Please describe.**

We'd benefit greatly from the IIS collector on our project. You think you could add this? https://github.com/prometheus-community/windows_exporter/blob/master/docs/collector.iis.md

**Describe the solution you'd like**

IIS collector supported on Fluent-bit windows_exporter_metrics input.

**Describe alternatives you've considered**

Technically it would be possible to create a custom solution to use the collector and export its metrics, but we'd rather have it as a part of the Fluent-bit package to minimize any future incompatibility problems.

**Additional context**

We want to be able to monitor and analyze IIS behavior in detail, including but not limited to application pool running state, number of concurrent requests, number of application pool recycles, etc. This would complement our existing monitoring tools quite nicely and provide additional means for debugging.

Thank you!