"Create a New Site" link on My Sites is inconsistent with other "Add New" links

[helen]

We have a class of .page-title-action (previously .add-new-h2) that's used in many other places, like Posts and Plugins and Themes. This one should be consistent as well. See below for a representative screenshot.

[JeffMatson]

Should be fixed in the above. First patch so bear with me. ;)

[helen]

@JeffMatson Thanks for the patch. Notes:

• The link needs to be moved to be next to the page title, which you should be able to find in wp-admin/my-sites.php.
• Please create patches from the root of the checkout - patch can't apply the patch without a path and there are often multiple files named the same but in different directories.

[JeffMatson]

Changes done. If I'm missing anything else, let me know.

[SergeyBiryukov]

In 34979:

My Sites: Make "Create a New Site" link consistent with other "Add New" links.

Props JeffMatson.
Fixes #34179.