Update SP1.8

In this small update we made some fixes and added some new features.
- Assemblies - External References: Unable to Browse Files while opening a Drawing or Assembly with missing referenced files.
- Note: The SOLIDWORKS 2021 SP1.8 point release contains this fix. This hotfix should only applied if using SOLIDWORKS 2021 SP4.0.
- SOLIDWORKS 2020 crashes when Lightweight components are hidden and shown.