5.8 make workflows callable

[desrosj]

Includes https://core.trac.wordpress.org/changeset/52179.

Includes https://core.trac.wordpress.org/changeset/56831 and https://core.trac.wordpress.org/changeset/57249.

Trac ticket: https://core.trac.wordpress.org/ticket/61213

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Props desrosj.

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[github-actions]

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[desrosj]

Merged in https://core.trac.wordpress.org/changeset/58597.