Add Vue export (#2145)

[brtinney]

Adds an export to be able to reference the Vue file.

[arnog]

Thanks for the PR!

[digitalboy]

Uncaught (in promise) TypeError: this.$el.setOptions is not a function at Proxy.<anonymous> (vue-mathlive.mjs:2:632)

My VUE code

<!-- MathLiveComponent.vue -->
<template>
    <mathlive-mathfield :id="mathfieldId" :value="mathFieldValue" :options="mathFieldOptions" @input="onInput">
    </mathlive-mathfield>
</template>

<script lang="ts">
import { defineComponent, ref } from 'vue';
import MathLiveVue from 'mathlive/vue';

export default defineComponent({
    name: 'MathLiveComponent',
    components: {
        'mathlive-mathfield': MathLiveVue
    },
    setup() {
        const mathfieldId = ref('mathfield');
        const mathFieldValue = ref('');
        const mathFieldOptions = ref({ /* ...options here... */ });

        const onInput = (event: Event) => {
            mathFieldValue.value = (event.target as HTMLInputElement).value;
        };

        return { mathfieldId, mathFieldValue, onInput, mathFieldOptions };
    },
});
</script>