Add builtin functions Core._import, Core._using; implement import/using logic in Julia (JuliaLang#57965)

Currently, `import` and `using` statements are compiled into calls to
`jl_toplevel_eval` with the Expr as an argument.  It can be useful in an
interactive environment to do import/using programmatically, for which
`eval(Expr(:import, ...))` or a macro is the only option at the moment
(see for example `InteractiveUtils.@activate`).

This PR adds two functions, `_module_import ` and `_module_using`, with
these signatures, and removes `Expr(:import/:using, ...)` from the lowered IR:

```
_module_import(explicit::Bool, to::Module, ctx::Union{Expr, Nothing}, names::Expr...)
_module_using(to::Module, from::Expr{Symbol})
```

## Lowering example

`import` statements and `using X:` statements are lowered to
`_module_import` like so:

```
import A             => _module_import(true,  Main, nothing,          Expr(:., :A))
import A.b           => _module_import(true,  Main, nothing,          Expr(:., :A, :b))
import A.b as c      => _module_import(true,  Main, nothing,          Expr(:as, Expr(:., :A, :b), :c))
import A.B: C.d, e   => _module_import(true,  Main, Expr(:., :A, :B), Expr(:., :C, :d), Expr(:., :e))
import A.B: C.d as e => _module_import(true,  Main, Expr(:., :A, :B), Expr(:as, Expr(:., :C, :d), :e))
using  A.B: C.d, e   => _module_import(false, Main, Expr(:., :A, :B), Expr(:., :C, :d), Expr(:., :e))
```

Plain `using` statements become `_module_using`:

```
using A.B            => _module_using(Main, Expr(:., :A, :B))
```

Multiple comma-separated `using` or `import` paths are lowered to
multiple calls to the appropriate builtin:
```
julia> Meta.@lower using A.B, C
:($(Expr(:thunk, CodeInfo(
1 ─       builtin Core._module_using(Main, $(QuoteNode(:($(Expr(:., :A, :B))))))
│         builtin Core._module_using(Main, $(QuoteNode(:($(Expr(:., :C))))))
│       $(Expr(:latestworld))
└──     return nothing
))))
```

Author: xal-0

src/Compiler.jl

@@ -65,7 +65,7 @@ using Base: @_foldable_meta, @_gc_preserve_begin, @_gc_preserve_end, @nospeciali
     structdiff, tls_world_age, unconstrain_vararg_length, unionlen, uniontype_layout,
     uniontypes, unsafe_convert, unwrap_unionall, unwrapva, vect, widen_diagonal,
     _uncompressed_ir, maybe_add_binding_backedge!, datatype_min_ninitialized,
-    partialstruct_init_undefs, fieldcount_noerror
+    partialstruct_init_undefs, fieldcount_noerror, _eval_import, _eval_using
 using Base.Order
 
 import Base: ==, _topmod, append!, convert, copy, copy!, findall, first, get, get!,