[REPLCompletions] enable aggressive inference for uncached child frames (#51503)
The REPL completion engine employs aggressive inference (incorporating
aggressive global binding resolution and aggressive concrete evaluation,
ignoring `:consistent`-cy), enabling completions in scenarios such as:
```julia
julia> d = Dict{Symbol,Any}(:key => Any[Some(r"x")])
julia> d[:key][1].value.<TAB>
compile_options
match_options
pattern
regex
```
While this approach has proven to be quite effective, it has its
limitations, given that aggressive inference was only activated for the
top-level representing an input code. Therefore, it fails to apply to
general cases like:
```julia
julia> getkeyelem(d) = d[:key][1]
julia> getkeyelem(d).<TAB> # no TAB completion
```
This limitation is the underlying cause of the first part of #51499.
To rectify this, the commit implements the following:
1. generalizes aggressive inference to apply to all child frames, when
they are not cached.
2. enables aggressive constant propagation, allowing the propagation of
mutable Consts.
With these changes, now we can get:
```julia
julia> getkeyelem(d). # TAB completes
julia> getkeyelem(d).value.
compile_options
match_options
pattern
regex
```
In conjunction with #51502, this resolves #51499.
julia
292562ce - [REPLCompletions] enable aggressive inference for uncached child frames (#51503)
