Extend size and variant prop types

[ghsteff]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[x] Other... Please describe: improvement

What is the current behavior?

You can't easily add extra sizes or variants to components

What is the new behavior?

You can add custom sizes or variants to multiple component themes

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

e.g. custom destructive button variant

<Button
  theme={extendComponentTheme<ButtonTheme>(buttonTheme, {
    variants: {
      destructive: 'bg-red-500 hover:bg-red-600 border-red-500 text-white'
    }
  })}
  variant="destructive"
>
  Destructive
</Button>

e.g. custom XL radio button size

<Radio
  theme={extendComponentTheme<RadioTheme>(radioTheme, {
    sizes: {
      xl: 'h-8 w-8'
    },
    indicator: {
      sizes: {
        xl: 'w-6 h-6'
      }
    }
  })}
  size="xl"
  label="XL"
/>

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[amcdnl]

we need to add docs for this