Query: Add is_post_format_archive() conditional tag

[irozum]

Adds a new is_post_format_archive( $post_formats = '' ) conditional tag, plus the matching WP_Query::is_post_format_archive() method, so themes and plugins can check whether the current query is for a post format archive without going through the less-intuitive is_tax( 'post-format', 'post-format-image' ) call and manually prefixing term slugs.

The implementation mirrors the existing has_post_format() helper's slug-prefixing pattern and follows the exact structure of sibling conditional tags like is_category()/is_tag()/is_tax(): a thin WP_Query method delegating to is_tax( 'post_format', ... ), plus a global wrapper function in query.php with the standard "query hasn't run yet" _doing_it_wrong() guard. is_post_format_archive was also added to the shared assertQueryTrue() conditional list in abstract-testcase.php (alongside is_post_type_archive) so it participates in the existing cross-conditional assertions, and it's automatically covered by the existing data_conditional_tags_trigger_doing_it_wrong_and_return_false_if_wp_query_is_not_set data provider since that discovers all is_* methods on WP_Query dynamically.

$post_formats accepts a single format string (e.g. 'aside') or an array of formats, without the post-format- slug prefix, matching the ergonomics of has_post_format().

Trac ticket: https://core.trac.wordpress.org/ticket/23749

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Opus 5
Used for: Implementation, tests, and PR description. Reviewed by Igor Rozum.

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