- Bake precompilepkgs into the sysimage
- Enable compilation in stdlib JLLs @staticfloat I guess this is ok now
we have pkgimages?
- Add some hardcoded precompiles encountered locally
- Disable a problematic llvm test, with a note

With this there's no compilation loading Pkg in interactive mode
```
% ./julia --trace-compile=stderr --start=no -q
julia> ]
(@v1.12) pkg> 
```

Before
```
% time julia +nightly --start=no --trace-compile=stderr -q -e "using Pkg"
precompile(Tuple{typeof(Base.setindex!), Base.Dict{Symbol, Union{Nothing, Bool, Int64, String}}, Int64, Symbol})
precompile(Tuple{typeof(Base.haskey), Base.Dict{String, Any}, String})
precompile(Tuple{typeof(MbedTLS_jll.__init__)})
precompile(Tuple{typeof(LibSSH2_jll.__init__)})
precompile(Tuple{typeof(LibGit2_jll.__init__)})
precompile(Tuple{typeof(nghttp2_jll.__init__)})
precompile(Tuple{typeof(LibCURL_jll.__init__)})
precompile(Tuple{typeof(MozillaCACerts_jll.__init__)})
precompile(Tuple{typeof(Base.Filesystem.normpath), String, String, Vararg{String}})
precompile(Tuple{typeof(p7zip_jll.__init__)})
precompile(Tuple{typeof(p7zip_jll.init_p7zip_path)})
precompile(Tuple{typeof(Base.append!), Array{String, 1}, Array{String, 1}})
precompile(Tuple{typeof(Base.join), Array{String, 1}, Char})
julia +nightly --start=no --trace-compile=stderr -q -e "using Pkg"  1.48s user 0.40s system 206% cpu 0.910 total
```
PR
```
% time ./julia --start=no --trace-compile=stderr -q -e "using Pkg"
./julia --start=no --trace-compile=stderr -q -e "using Pkg"  1.62s user 0.13s system 402% cpu 0.433 total
```