chore(button): design refinements

[dancormier]

Note
Please don't merge before creating a plan to communicate the deprecation of muted+filled

---

STACKS-339

This PR implements button design refinements as part of the design vision changes to Stacks. cc @PiperLawson

How to test

Hit up the buttons docs page in the deploy preview. The buttons should match the Figma design spec at the end of this PR description. Test out combinations of light/dark and high contrast modes.

TODO

• Remove border on filled variations
• Remove inset shadow on filled variations
• Darken type of muted button styles
• Lighten border color of muted button styles
• Deprecate muted+filled button style
• Ensure visual regression tests pass
• Create a plan to communicate the deprecation of muted+filled

Details about changes in this PR

• You'll notice > 3,000 files changed. Nearly all are visual regression test baseline images, since we have > 1,000 images for button being tested against three different browsers
• A deprecated warning has been added to the button docs for the muted+filled style and the exampled for that style in combination with loading and dropdown has been removed from the docs to discourage usage

Figma

[netlify]

✅ Deploy Preview for stacks ready!

Name	Link
🔨 Latest commit	9d427f9
🔍 Latest deploy log	https://app.netlify.com/sites/stacks/deploys/64b5517bd5c74500086520da
😎 Deploy Preview	https://deploy-preview-1421--stacks.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for stacks ready!

Name	Link
🔨 Latest commit	0758bb2
🔍 Latest deploy log	https://app.netlify.com/sites/stacks/deploys/64bacc3f813a3d00089b5f8a
😎 Deploy Preview	https://deploy-preview-1421--stacks.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.