Reuse parsed modules

[kubouch]

Description

Similar to #8949, Nushell reuses parsed module if the same file is being parsed again.

Benchmarks

(results rounded to milliseconds, the mean values from bench vary within +-1 ms)

Baseline

Overhead of calling nu on empty file:

> touch empty.nu
> bench { nu empty.nu } | get mean
~40ms
> bench { /home/kubouch/.cargo/target/release/nu empty.nu } | get mean
~40ms

Benchmark 1

Repeated calls to use

# test.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu
use crates/nu-std/lib/mod.nu

Old vs. new running times:

> use std bench
> bench { nu test.nu } | get main  
~128ms (+88 ms from baseline)
> bench { /home/kubouch/.cargo/target/release/nu test.nu } | get mean
~47ms (+7 ms from baseline)

Benchmark 2

Real project which reuses a utils module in several files (https://github.com/kubouch/nuun, commit 5bf92d799d1561ddebd329c3e8106d575f4c8fa0)

# test_nuun.nu
use /home/kubouch/git/nuun/nuun/

> use std bench
> bench { nu test_nuun.nu } | get main  
~48 ms (+8 ms from baseline)
> bench { /home/kubouch/.cargo/target/release/nu test_nuun.nu } | get mean
~46 ms (+6 ms from baseline)

User-Facing Changes

Speedup if parsing the same file more than once as a module.

Tests + Formatting

After Submitting

[codecov]

Codecov Report

Merging #9125 (ad19e24) into main (0ea973b) will increase coverage by 0.00%.
The diff coverage is 96.66%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9125   +/-   ##
=======================================
  Coverage   68.79%   68.80%           
=======================================
  Files         641      641           
  Lines      102104   102122   +18     
=======================================
+ Hits        70243    70264   +21     
+ Misses      31861    31858    -3     

Impacted Files	Coverage Δ
crates/nu-parser/src/parse_keywords.rs	77.75% <92.30%> (+0.05%)	⬆️
crates/nu-protocol/src/engine/engine_state.rs	86.51% <100.00%> (+0.12%)	⬆️

... and 1 file with indirect coverage changes