Add support for Hugo (GFM, Obsidian) Markdown alert syntax

[chalin]

Tasks

• Add Hugo Markdown-style alert support and docs #2443
• Prep: Migrate i18n files from TOML to YAML and add conversion scripts #2447
• Add support for custom attributes in blockquote alerts #2452
• i18n:
  • Add alert labels to selected i18n files #2450
  • Convert most shortcode alerts to markdown, and more #2457
  • Add Bengali translations for alert labels #2459
  • Convert Chinese i18n files from TOML to YAML #2461
  • Add alert label translations for zh-cn and zh-tw #2462
  • Convert Japanese translations from TOML to YAML #2463
  • Add alert labels and all-rights-reserved in Japanese #2464
  • Convert Hebrew translation file to YAML #2466
  • Add alert and table of contents labels to Hebrew i18n #2467
  • Convert all remaining i18n files to YAML, add helper scripts #2468
• ...

References

• https://gohugo.io/render-hooks/blockquotes/#alerts
• https://docs.github.com/en/contributing/style-guide-and-content-model/style-guide#alerts
• https://github.blog/changelog/2023-12-14-new-markdown-extension-alerts-provide-distinctive-styling-for-significant-content/
• Later release? Add support for foldable Obsidian-style alerts/callouts #2474

Consider driving them from the same map as BS uses to generate its alerts. This way, if a project extends that map, we will take it into account.

Later

• Add support for foldable Obsidian-style alerts/callouts #2474

[chalin]

/cc @svrnm