[rush] Address an issue where filtered installs cause repeated rush installs

[william2958]

Summary

Currently, rush will always consider a filtered install as requiring a clean install. This MR adds the metadata information to the last install flag file, so rush can detect if a clean install is necessary even when it is a filtered install. Code from the "split workspace" PR: https://github.com/microsoft/rushstack/pull/3481

Details

How it was tested

Impacted documentation