Add markdown formatter toolbar action

[apples-kksk]

Fixes #756.

Summary

• add a toolbar action that formats the current markdown document with the existing Prettier dependency
• support formatting the current selection when text is selected
• preserve cursor position after formatting and avoid adding a final newline when the original text did not have one

Testing

• npx prettier --check src/cloud/components/Editor/EditorToolbar.tsx src/cloud/lib/editor/formatMarkdown.ts src/cloud/lib/i18n/types.ts src/cloud/lib/i18n/enUS.ts src/cloud/lib/i18n/zhCN.ts src/cloud/lib/i18n/ja.ts src/cloud/lib/i18n/fr.ts typings/prettier.d.ts
• npx eslint src/cloud/components/Editor/EditorToolbar.tsx src/cloud/lib/editor/formatMarkdown.ts src/cloud/lib/i18n/types.ts src/cloud/lib/i18n/enUS.ts src/cloud/lib/i18n/zhCN.ts src/cloud/lib/i18n/ja.ts src/cloud/lib/i18n/fr.ts typings/prettier.d.ts --ext .ts,.tsx
• npx tsc --noEmit --pretty false

IssueHunt: https://issuehunt.io/r/BoostIO/BoostNote-App/issues/756

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #756: Introduce content formatter

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