Improve the diagnostic UX when a missing PDB is encountered

[MichaelSimons]

The diagnostic UX when a missing PDB is encountered is not great. In discussing this with @NikolaMilosavljevic, it is most likely the case that the dll which doesn't have a pdb is not produced from the build. It is likely it is from PSB or SBRP. The message emitted by the build provides no information to aid in determining this as was the case in this PR. In this case, the dll was picked up from PSB.

/__w/1/vmr/eng/finish-source-only.proj(95,5): warning : Did not find PDBs for the following SDK files:
/__w/1/vmr/eng/finish-source-only.proj(95,5): warning : sdk/10.0.100-preview.4.25203.1/Microsoft.ApplicationInsights.dll
/__w/1/vmr/eng/finish-source-only.proj(95,5): warning : sdk/10.0.100-preview.4.25203.1/DotnetTools/dotnet-watch/10.0.100-preview.4.25203.1/tools/net10.0/any/Microsoft.ApplicationInsights.dll

To help make this message more actionable, consider the following changes:

1. Include the assembly version in the output.
2. Include suggestions to diagnose. The first would be to suggest ensuring this dll was produced by the build and not picked up from PSB or SBRP. This could be embedded in the message or the message could link to external documentation.