feat(styles): add skeleton sass modules and stories

[jnm2377]

Closes #9130

New

• adds skeleton styles to sass modules
• adds SkeletonPlaceholder and SkeletonText to @carbon/react stories

Testing / Reviewing

• ensure all test pass
• look at the carbon-next deploy preview and go to Skeleton stories, verify that styles are rendering correctly (can cross reference current storybook styles)

[netlify]

✔️ Deploy Preview for carbon-react-next ready!

🔨 Explore the source changes: 356d4b9

🔍 Inspect the deploy log: https://app.netlify.com/sites/carbon-react-next/deploys/611eb84e94487b00075a44b6

😎 Browse the preview: https://deploy-preview-9423--carbon-react-next.netlify.app

[netlify]

✔️ Deploy Preview for carbon-elements ready!

🔨 Explore the source changes: 356d4b9

🔍 Inspect the deploy log: https://app.netlify.com/sites/carbon-elements/deploys/611eb84e73b11400089e9223

😎 Browse the preview: https://deploy-preview-9423--carbon-elements.netlify.app

[netlify]

✔️ Deploy Preview for carbon-components-react ready!
Built without sensitive environment variables

🔨 Explore the source changes: 356d4b9

🔍 Inspect the deploy log: https://app.netlify.com/sites/carbon-components-react/deploys/611eb84ea96cb70007878aa8

😎 Browse the preview: https://deploy-preview-9423--carbon-components-react.netlify.app

[sstrubberg]

Getting a fail on the skeleton test.

[jnm2377]

@tay1orjones looks like the percy snapshot for CodeSnippet is failing bc in the snapshot it's missing the show more button. I checked out the story and it's there, it just took a second to load. I'm not touching any codesnippet styles here. Any thoughts on what I should do?

[tay1orjones]

@jnm2377 interesting! My first thought is to modify the codesnippet vrt and make sure cy.findByText('show more').should('be.visible') before the cypress snapshot is taken

[jnm2377]

@tw15egan @sstrubberg sorry for the delay, this is ready for re-review now.

[tw15egan]

LGTM 👍 ✅