Block Themes: Ensure that `_build_block_template_result_from_file()` injects `theme` attribute#5186

ockham wants to merge 11 commits intoWordPress:trunkWordPress/wordpress-develop:trunkfrom

ockham:add/test-coverage-for-build-block-template-result-from-file-theme-data-attributeockham/wordpress-develop:add/test-coverage-for-build-block-template-result-from-file-theme-data-attributeCopy head branch name to clipboard