Remove redundant repeated CSS

[kong0107]

Expected Behavior

CSS codes do not repeat.

Current Behavior

CSS codes are repeatedly written out
if there are more than one author box in one page
even when they may share same styles.

Besides MA_Default_Layouts::renderBoxHTML may be called multiple times,
each shortcode would lead a <style> even when there's already the same CSS code.

Possible Solution

Check if the style codes have been added or enqueued before calling wp_add_inline_style and wp_enqueue_style.

Steps to Reproduce (for bugs)

Use more than one [publishpress_authors_box] in single page.

Context

HTML could and shall be less.

Your Environment

• Version used: 4.7.3
• Browser Name and version: MS Edge 131.0.2903.146
• Operating System and version (desktop or mobile): Windows 11 24H2 on desktop