feat: adding `required` property to input attributes

[SantosDiv]

Added the required property to delegate to the component itself the responsibility of understanding how to define this characteristic. This makes required easier to use, making it similar to the select tag in HTML.

[netlify[bot]]

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🔨 Latest commit	be023300ddafff909acf9651e8a8dd648ad8910a

[sagalbot]

Unfortunately this won't work. The search input doesn't actually bind a value from the options, its value is the search string. For this to work, it'd have to be implemented this way: https://vue-select.org/guide/validation.html?#required