Trimmed assemblies should not contain sig and opt data

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

F# assemblies in a trimmed application contain signature and optimization data.

**Describe the solution you'd like**

These resources serve no purpose in a deployed application and should be stripped.

**Describe alternatives you've considered**

A post-build task that iterates over and modifies the emitted assemblies.

**Additional context**

8.0.100-preview.6.23330.14