Allow `using Mod as NewName` in v1.13+

[LilithHafner]

WIP c.f. https://github.com/JuliaLang/julia/issues/52784

There will also need to be changes to eval, though I think lowering already supports this.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a6f2d15) 94.61% compared to head (229a4e2) 96.54%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #406      +/-   ##
==========================================
+ Coverage   94.61%   96.54%   +1.92%     
==========================================
  Files          14       14              
  Lines        4178     4195      +17     
==========================================
+ Hits         3953     4050      +97     
+ Misses        225      145      -80     

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[c42f]

Heya, we just moved JuliaSyntax into Base in https://github.com/JuliaLang/julia/pull/59870 - if you want to re-propose this PR over there, I've created a branch https://github.com/JuliaLang/JuliaSyntax.jl/tree/pr-for-Base/406 to make this easier.

To make use of the branch, you can use the following steps:

• Clone JuliaLang/julia
• Add JuliaSyntax as a git remote
• Check out pr-for-Base/406
• Rebase on top of master

For example:

# git clone [email protected]:JuliaLang/julia julia_dir
# cd julia_dir

git remote add JuliaSyntax [email protected]:JuliaLang/JuliaSyntax.jl
git fetch JuliaSyntax
git checkout pr-for-Base/406
git rebase origin/master

Sorry this wasn't dealt with prior to the big move!