fix: unauthorized template creation from history

[Schwehn42]

Description

Previously, users could create templates from boards even if they weren't allowed to look at custom templates.

This has been fixed, following the same logic of the templates:
users may create templates iff:

• they are anonymous OR
• SCRUMLR_ALLOW_ANONYMOUS_CUSTOM_TEMPLATES=false

Changelog

• only display create template from board mini menu item if users are allowed to see custom templates
• refactor to make conditional mini menu array item entries look cleaner

Checklist

• I have performed a self-review of my own code
• I have written and understand every part of this contribution myself - if AI tools were used, I have thoroughly reviewed and verified all changes
• I have commented my code, particularly in hard-to-understand areas

[github-actions]

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Deployed Images

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[Planlos5000]

LGTM