Avoid side effects when precompiling find_artifact_dir

[giordano]

With an explicit call to find_artifact_dir() we were actually fetching lazy artifacts during precompilation, which is typically undesired, besides hitting a bug in Downloads.jl in certain versions of Julia (up to 1.10.4) which causes the download of the artifact to hang. Instead, with Base.precompile we retain the caching of native code, without causing extra downloads during precompilation.

Some benchmarks, same as in #53. Before this PR:

julia> @time_imports using LLVMExtra_jll
      0.2 ms  LazyArtifacts
     13.6 ms  Preferences
      0.4 ms  JLLWrappers
               ┌ 6.8 ms LLVMExtra_jll.__init__() 59.45% compilation time
     50.7 ms  LLVMExtra_jll 92.31% compilation time

With this PR:

julia> @time_imports using LLVMExtra_jll
      0.2 ms  LazyArtifacts
     14.2 ms  Preferences
      0.5 ms  JLLWrappers
               ┌ 6.7 ms LLVMExtra_jll.__init__() 59.63% compilation time
     50.4 ms  LLVMExtra_jll 92.59% compilation time

So there's no penalty in using Base.precompile. If I remove the forced precompilation entirely:

julia> @time_imports using LLVMExtra_jll
      0.2 ms  LazyArtifacts
     10.2 ms  Preferences
      0.4 ms  JLLWrappers
               ┌ 4.5 ms LLVMExtra_jll.__init__() 58.45% compilation time
     52.4 ms  LLVMExtra_jll 94.76% compilation time

This is slower than with the precompilation call, but not as bad as in #53.

Also, with this PR:

(@v1.10) pkg> add IntelOpenMP_jll
   Resolving package versions...
   Installed IntelOpenMP_jll ─ v2024.2.1+0
    Updating `~/.julia/environments/v1.10/Project.toml`
  [1d5cc7b8] + IntelOpenMP_jll v2024.2.1+0
    Updating `~/.julia/environments/v1.10/Manifest.toml`
  [1d5cc7b8] + IntelOpenMP_jll v2024.2.1+0
Precompiling project...
  1 dependency successfully precompiled in 1 seconds. 56 already precompiled.

julia> using IntelOpenMP_jll
  Downloaded artifact: IntelOpenMP

julia>

Download happens at using-time, not during precompilation, as intended. Note that I'm using Julia 1.10.4, which would also cause the precompilation to last at least 30 seconds because of the Downloads.jl bug.

Fix #65.

[topolarity]

Thanks @giordano !