[P5Lab] Move and rename animation metadata scripts

[ajpal]

Another pure refactor. Just renaming from camelCase to snake_case because these are Ruby scripts. Also moving from code-dot-org/tools/scripts to code-dot-org/bin/animation_assets, which I think will make these easier to find moving forward.

Links

jira

Testing story

Just moving existing scripts, so no additional tests. As a sanity check, I ran rebuild_animation_metadata for spritelab just to make sure it still worked. I didn't test all the scripts, though.

Deployment strategy

Follow-up work

Privacy

Security

Caching

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[epeach]

Looks good! This is going to confuse my Javascript-based brain, but it's definitely good to align with standards here.