Exceptions in workload shouldn't prevent compilation

Currently, whenever the compile_workload throws an exception, the package becomes effectively uninstallable.
That's especially bad for packages with comprehensive precompilation workloads: they become impossible to install and use in any capacity even when a tiny part of their functionality is broken by Julia / dependencies update.

Compile workload errors should just be turned into a small warning, like "precompilation workload failed, not all functionality may be available".

Start by locating the compile_workload handling in PrecompileTools.jl and inspect how exceptions currently affect package installation or precompilation. Confirm the existing behavior, then verify that a workload exception produces the requested warning while the package remains usable and other precompilation can continue.

Written by the indexing model from the issue text.