Add primitive integration with JuliaLowering

[aviatesk]

Add primitive integration with JuliaLowering

This implements a very basic integration with JL.

You can retrieve inferred trees in the following way:

julia> using JET, JuliaSyntax

julia> result = @report_call sum("julia")
═════ 2 possible errors found ═════
┌ sum(a::String) @ Base ./reduce.jl:553
│┌ sum(a::String; kw::@Kwargs{}) @ Base ./reduce.jl:553
││┌ sum(f::typeof(identity), a::String) @ Base ./reduce.jl:524
│││┌ sum(f::typeof(identity), a::String; kw::@Kwargs{}) @ Base ./reduce.jl:524
││││┌ mapreduce(f::typeof(identity), op::typeof(Base.add_sum), itr::String) @ Base ./reduce.jl:299
│││││┌ mapreduce(f::typeof(identity), op::typeof(Base.add_sum), itr::String; kw::@Kwargs{}) @ Base ./reduce.jl:299
││││││┌ mapfoldl(f::typeof(identity), op::typeof(Base.add_sum), itr::String) @ Base ./reduce.jl:167
│││││││┌ mapfoldl(f::typeof(identity), op::typeof(Base.add_sum), itr::String; init::Base._InitialValue) @ Base ./reduce.jl:167
││││││││┌ mapfoldl_impl(f::typeof(identity), op::typeof(Base.add_sum), nt::Base._InitialValue, itr::String) @ Base ./:36
│││││││││┌ foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, nt::Base._InitialValue, itr::String) @ Base ./:40
││││││││││┌ _foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, init::Base._InitialValue, itr::String) @ Base ./reduce.jl:54
│││││││││││┌ (::Base.BottomRF{typeof(Base.add_sum)})(acc::Char, x::Char) @ Base ./:78
││││││││││││┌ add_sum(x::Char, y::Char) @ Base ./:16
│││││││││││││ no matching method found `+(::Char, ::Char)`: (x::Char + y::Char)
││││││││││││└────────────────────
│││││││││┌ foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, nt::Base._InitialValue, itr::String) @ Base ./:41
││││││││││┌ reduce_empty_iter(op::Base.BottomRF{typeof(Base.add_sum)}, itr::String) @ Base ./:372
│││││││││││┌ reduce_empty_iter(op::Base.BottomRF{typeof(Base.add_sum)}, itr::String, ::Base.HasEltype) @ Base ./:373
││││││││││││┌ reduce_empty(op::Base.BottomRF{typeof(Base.add_sum)}, ::Type{Char}) @ Base ./:349
│││││││││││││┌ reduce_empty(::typeof(Base.add_sum), ::Type{Char}) @ Base ./:342
││││││││││││││┌ reduce_empty(::typeof(+), ::Type{Char}) @ Base ./:335
│││││││││││││││ no matching method found `zero(::Type{Char})`: zero(T::Type{Char})
││││││││││││││└────────────────────

julia> inferred = JET.get_trees(result, :add_sum)
1-element Vector{JuliaLowering.SyntaxTree}:
 (method core.nothing %₈ (code_info (block Base.+ (call %₁ slot₂/x slot₃/y) (return %₂))))

julia> JuliaSyntax.sourcetext(inferred[1])
"add_sum(x, y) = x + y"

There are several things to note:

• Please run Pkg.instantiate() after checking out to this branch to
  install JL
• I couldn't think of a good way to integrate this system with the existing
  cache system, so for now I disabled all the global cache for now on
  this branch.
• In cases where retrieval of the JL.SyntaxTree corresponding to the
  target CodeInfo for inference fails, no inferred tree will exist.
  Currently, retrieval likely doesn't work well for keyword methods and
  methods with default arguments eit

[mlechu]

Suggested change

	JL.lower(m.module, st0)
	JL.lower(m.module, st0; expr_compat_mode=true)

Do we want expr_compat_mode on here? The types of quoted code and the signatures of new macro definitions will be different otherwise.