Add `Compiler._verify_trim_world_age` for better printing
The `juliac-buildscript` is quite aggressive in how it modifies type
printing, so caching the pre-buildscript world like this allows us
to print stacktraces in their usual fidelity.
Before:
```
[1] get_size_dict!(ne::StaticNestedEinsum{Char, ?, ?}, xs::Any, size_info::Dict{Char, Int64})
@ OMEinsum ~/.julia/dev/OMEinsum/src/einsequence.jl:269
...
```
After:
```
[1] get_size_dict!(ne::StaticNestedEinsum{Char, nothing, ('j','k','l')}, xs::Any, size_info::Dict{Char, Int64})
@ OMEinsum ~/.julia/dev/OMEinsum/src/einsequence.jl:269
...
```
