Live preview link in Themes.trac tickets outdated

[dd32]

The "Live preview" link in the theme updates tickets are using outdated steps. We should probably update to the latest steps.

hook.js:608 The "importFile" step is deprecated. Use "importWxr" instead.
hook.js:608 The "pluginZipFile" option of the "installPlugin" step is deprecated. Use "pluginData" instead.
hook.js:608 The "themeZipFile" option of the "installTheme" step is deprecated. Use "themeData" instead.
hook.js:608 The "themeZipFile" option of the "installTheme" step is deprecated. Use "themeData" instead.

The testdata appears to have some CORS issues fetching images still, see ​https://github.com/WordPress/theme-test-data/pull/89

The WXR Step is also triggering a error at present null function or function signature mismatch unsure if that's theme directory specific.

Test using the latest ticket: ​https://themes.trac.wordpress.org/query?desc=1&order=id

[rollybueno]

I reported the same to Playground ​https://github.com/WordPress/wordpress-playground/issues/2548 a week ago.

See https://meta.trac.wordpress.org/ticket/8077

This updates the preview endpoint to handle theme previews for themes.trac, and adds a few options.

This is still in need of a cleanup I suspect, so PR'ing it for now.

[dd32]

In 14523:

Theme Directory: Upgrade the blueprint used for Theme Review live previews.

This removes the blueprint from being static in the trac ticket, allowing for future maintenance not to break older links.

Fixes #8077.
Merges ​https://github.com/WordPress/wordpress.org/pull/506.
See ​https://github.com/WordPress/wordpress-playground/issues/2548.