Proposal: Allow overwriting static utilities that have a namespace

[philipp-spiess]

This PR attempts to move static utilities that are overwriteable by a theme value to be a fallback rather than a conflicting implementation. The idea is to allow a theme value to take presedence over that static utility and cause it not to generate.

For example, when overwriting the --radius-full variant, it should ensure that the default rounded-full no longer emits the calc(infinity * 1px) declaration:

expect(
  await compileCss(
    css`
      @theme {
        --radius-full: 99999px;
      }
      @tailwind utilities;
    `,
    ['rounded-full'],
  ),
).toMatchInlineSnapshot(`
  ":root, :host {
    --radius-full: 99999px;
  }

  .rounded-full {
    border-radius: var(--radius-full);
  }"
`)

This allows anyone who wants --radius-full to be a CSS variable to simply define it in their theme:

@theme {
  /* Make `--radius-full` a CSS variable without the utility generating two CSS classes */
  --radius-full: calc(infinity * 1px);
}

The idea is to extend this pattern across all functional utilities that also have static utilities that can collide with the namespace. This gives users more control over what they want as CSS variables when the defaults don't work for them, allowing them to resolve #16639 and #15115 in user space.