Media: Add tests for get_media_embedded_in_content()

[itzmekhokan]

get_media_embedded_in_content() has two tests in tests/phpunit/tests/media.php, both covering the same happy path: well-formed markup, one element per type.

This adds tests/phpunit/tests/media/getMediaEmbeddedInContent.php for the paths they leave out — the default $types argument, an empty array of types, the media_embedded_in_content_allowed_types filter narrowing and extending the list, repeated elements of one type, both self-closing forms, and markup the pattern is not meant to match. Fixtures sit inside surrounding content, matching the shape used in getTagRegex.php.

The repeated-element case pins the lazy body match that get_tag_regex() only just gained in [63331].

Trac ticket: https://core.trac.wordpress.org/ticket/65931

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Opus 5
Used for: characterizing the function's current behaviour and writing the test cases. All changes were reviewed and validated by me.

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