next(breaking): change checked type for checkbox components

[huntabyte]

Having the checked state be boolean | 'indeterminate' is quite annoying, especially considering from a user's perspective, once you leave the 'indeterminate' state, you can't toggle back to it.

This PR changes the checked props to be boolean and adds an indeterminate prop which is also of type boolean.

If you wish to have a checkbox in an indeterminate state, you can simply do the following:

<Checkbox.Root indeterminate />

By default, when a user clicks an indeterminate checkbox, it will change checked to true and indeterminate to false.

indeterminate can be controlled, so you can programmatically put a checkbox back into the indeterminate state if you wish, using the normal state management strategies (bind:indeterminate, onIndeterminateChange, controlledIndeterminate).

I've wanted to make this change for some time and many others have expressed frustration with always having to conditionally check the type when working with things that expect a boolean.

Additionally, the snippet props for the Checkbox and *Menu.CheckboxItem components have been adjusted to expose both a checked and indeterminate prop:

<Checkbox.Root>
	{#snippet children({ checked, indeterminate })}
		{#if indeterminate}
			-
		{:else if checked}
			✅
		{/if}	
	{/snippet}
</Checkbox.Root>

Closes #885

[changeset-bot]

🦋 Changeset detected

Latest commit: dcb5f06

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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bits-ui	Patch

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