Refactor: Move KclValue into its own module

[adamchalmers]

Just moving KclValue into its own file because executor.rs is huge. No behavioural changes.

[qa-wolf[bot]]

QA Wolf here! As you write new code it's important that your test coverage is keeping up. Click here to request test coverage for this PR!

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
modeling-app	✅ Ready (Inspect)	Visit Preview	Nov 21, 2024 4:17pm

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 58.36066% with 127 lines in your changes missing coverage. Please review.

Project coverage is 86.06%. Comparing base (c17cb10) to head (16a208d). Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/wasm-lib/kcl/src/kcl_value.rs	58.36%	127 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4535 +/- ## ========================================== + Coverage 86.04% 86.06% +0.02% ========================================== Files 80 81 +1 Lines 29492 29525 +33 ========================================== + Hits 25375 25410 +35 + Misses 4117 4115 -2 ``` | [Flag](https://app.codecov.io/gh/KittyCAD/modeling-app/pull/4535/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD) | Coverage Δ | | |---|---|---| | [wasm-lib](https://app.codecov.io/gh/KittyCAD/modeling-app/pull/4535/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD) | `86.06% <58.36%> (+0.02%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=KittyCAD#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles