Portal language selector

[isaac-vicentini]

PR Description:

A language selector widget for the Portal.
The user can change the instance language without having to leave the Portal.

• Displays a dropdown with flags and language names.
• Automatically updates the user's language in the sys_user table.
• Reloads the page to apply the new language immediately.

Pull Request Checklist

Overview

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• I have read and understood the CONTRIBUTING.md guidelines
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Code Quality

• My code is relevant to ServiceNow developers
• My code snippets expand meaningfully on official ServiceNow documentation (if applicable)
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• I've tested my code snippets in a ServiceNow environment (where possible)

Repository Structure Compliance

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Documentation

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Restrictions

• My PR does not include XML exports of ServiceNow records
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• My PR does not include changes that fall outside the described scope

[github-actions]

👋 Unassigning @Rampriya-S due to inactivity (> 60 min without comments/reviews). This PR remains open for other reviewers.

[ravichandra1998g]

looks good to me