Evaluate usage of Assembly.Location

.NET 5 changed some behavior wrt `Assembly.Location`, `Assembly.CodeBase`, etc, when sigle-file publishing is used. https://docs.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/5.0/assembly-api-behavior-changes-for-single-file-publish.

We need to evaluate this for v4 to see if these will affect us.

Start by searching the v4 codebase for usages of Assembly.Location, Assembly.CodeBase, and related assembly APIs. Compare each usage with the linked .NET 5 single-file publishing behavior and identify whether it is affected; done means the v4 impact has been evaluated and any affected areas are recorded for follow-up.

Written by the indexing model from the issue text.