Font Library: Center align "No fonts installed" message in library tab

[akasunil]

Description

Splitting it from #63740 (review)

Currently, When there are no font installed in font manager, it display No fonts installed. message on library tab of font manager. and It displayed at top-left corner.

It should aligned vertically and horizontally centered like we have in dataviews.

Step-by-step reproduction instructions

• Open site editor, and go to global styles
• Open font manager
• Uninstall all fonts
• No fonts installed. message will appear

Screenshots, screen recording, code snippet

Dataviews	Fonts library

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

[akasunil]

In order to address this, It require to update all parent elements styles to have full height in font library modal.