[7.x] Fix output of component attributes

[perifer]

Closes #31939

This PR fixes multiple issues with how component attributes are rendered. $attribute and $attributes->merge() results in different rendered attributes for values that are true or casts to false. For example min="0" is currently removed when using merge() (see full example below).

Here is an attempt to summarise the changes. In short $attribute and $attribute->merge() now have identical output and are rendered the same way as Vue.

<x-input :checked="false">, <x-input :checked="null">, <x-input :checked=""> → <input>
Previously <input checked=""> and <input>

<x-input :min="0">, <x-input :min="'0'"> → <input min="0">
Previously <input min="0"> and <input>

<x-input :checked="true"> → <input checked="checked">
Previously <input checked> and <input checked="checked">

This last example is handled a bit simpler than Vue. Vue differentiate boolean attributes (checked, disabled, itemscope etc) and normal attributes. This PR doesn't (but it could be added in another PR).

An example where min="0" is removed when using merge()

A blade component with attributes:

<input type="number" {{ $attributes }} />

For an input with type number it's reasonable to have min="0":

<x-number min="0" max="10" class="p-4" />

This render as:

<input type="number" min="0" max="10" class="p-4" />

But if you used merge():

<input type="number" {{ $attributes->merge(['class' => 'm-4']) }} />

The attribute with value 0 is removed:

<input type="number" max="10" class="p-4 m-4" />

Another example with an attribute with a value false that is rendered differently when using with or without merge()

With a component that simply prints it's attributes:

<input {{ $attributes }} />

If the component is used like this:

<x-input :disabled="false" />

We would expect the rendered template to be:

<input />

But the current implementation renders:

<input disabled="" />

But if the component uses merge() like this:

<input {{ $attributes->merge() }} />

The output is what one would expect:

<input />