Added "Create Script..." option to "Add Component..." ItemPicker

[adriengivry]

Description

This drastically improves the script creation flow!

• Added an option to create a new script directly from the "Add Component..." item picker
• The search filter is used as the default filename for the script
• Also fixed a bug where error message box aren't working on Linux

Related Issue(s)

Fixes #(issue number)

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AI Usage Disclosure

Generated new code

Checklist

• My code follows the project's code style guidelines
• When applicable, I have commented my code, particularly in hard-to-understand areas
• When applicable, I have updated the documentation accordingly
• My changes don't generate new warnings or errors
• I have reviewed and take responsibility for all code in this PR (including any AI-assisted contributions)