Add v8 engine to run JavaScript in puppy-browser

[lmt-swallow]

Description

This PR introduces V8 engine to puppy and enables to run scripts inside <script>. ダルくなってきているため雑にディレクトリ構造の修正もこの PR に纏めてしまった

Context

N/A

Checklist

• I opened a draft PR or added the [WIP] level if my PR is not ready for review.
• I have reviewed the code by myself.
• I have assigned an appropriate reviewer for the PR.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• I have added tests enough to show how your code behaves and that your code works as expected.

Additional Notes

N/A