Update CSS handles on ProductSpecification

[victorhmp]

What problem is this solving?

Review the available CSS handles on the ProductSpecification component, add new CSS handles:

• specificationsTablePropertyHeading
• specificationsTableSpecificationHeading
• specificationItemProperty
• specificationItemSpecifications

and also use vtex.css-handles app to resolve those handles.

How should this be manually tested?

Workspace

Checklist/Reminders

• Updated README.md.
• Updated CHANGELOG.md.
• Linked this PR to a Clubhouse story (if applicable).
• Updated/created tests (important for bug fixes).
• Deleted the workspace after merging this PR (if applicable).

Type of changes

✔️	Type of Change
_	Bug fix
✔️	New feature
_	Breaking change
✔️	Technical improvements

[vtex-io-ci-cd]

Hi! I'm VTEX IO CI/CD Bot and I'll be helping you to publish your app! 🤖

Please select which version do you want to release:

• Patch

• Minor

• Major

And then you just need to merge your PR when you are ready! There is no need to create a release commit/tag.

• No thanks, I would rather do it manually 😞

[vtex-io-docs-bot]

Beep boop 🤖

I noticed you didn't make any changes at the docs/ folder

• There's nothing new to document 🤔
• I'll do it later 😞

In order to keep track, I'll create an issue if you decide now is not a good time

• I just updated 🎉🎉

[vtex-io-docs-bot]

Beep boop 🤖 That's ok, I created an issue for this so we don't forget