Improve Assembler typography styles

[richtabor]

A few improvements I discovered as I research what folks are doing with the Assembler theme.

Changes proposed in this Pull Request:

• Closes Assembler: Move the style variation specific font families from the main theme.json to the variation json file. #8079
• Adjust size of default H4 to add more visual hierarchy.
• Disable background color picker on heading blocks.
• Reduce size of xx-large just a little.
• Remove "Rufina" variation; it's not strong and too similar to others.
• Add tweaks for site tagline in typography styles.
• Encompasses Assembler: Move the style variation specific font families from the main theme.json to the variation json file #8416 into this PR to prevent conflicts.

Site tagline

CleanShot.2024-11-15.at.16.40.47.mp4

H4 Before

H4 After

• props to @alaczek.

[github-actions]

Preview changes

I've detected changes to the following themes in this PR: Assembler.
You can preview these changes by following the links below:

• Preview changes for Assembler

I will update this comment with the latest preview links as you push more changes to this PR.

Note

The preview sites are created using WordPress Playground. You can add content, edit settings, and test the themes as you would on a real site, but please note that changes are not saved between sessions.

[github-actions]

Theme-Check results

assembler: No changes required ✅.

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[github-actions]

Theme-Check results

assembler: No changes required ✅.

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