feat(i18n): do not use legacy api

[davidglezz]

Pull request template

Motivation and context

Initialise i18n without legacy api.
This allows us to use the composable useI18n()

i18n.global.locale is a ref in the new api as seen in the docs:
https://vue-i18n.intlify.dev/guide/essentials/scope.html#local-scope-1

This is a potential breaking change:

// New api
i18n.global.locale.value = 'en'

// legacy api:
i18n.global.locale = 'en'

• Dependencies. If any, specify:
• Open issue. If applicable, link:

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that causes existing functionality to not work as expected)
• Change requires a documentation update

What is the destination branch of this PR?

• Main
• Other. Specify:

How has this been tested?

Tests performed according to testing guidelines:

Checklist:

• My code follows the style guidelines of this project.
• I have performed a self-review on my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

[annacv]

Tested in x-archetype, no new warns