Docs: add missing docs to WP_oEmbed class

[ramiy]

Add missing docs to class properties.

Add missing @since and @access to methods.

See also: ticket #32246 (comment 325)

[DrewAPicture]

In 37067:

Docs: Improve and add missing DocBlocks for methods and properties in WP_oEmbed.

Props ramiy.
See #36296.

[DrewAPicture]

In 37068:

Docs: Use third-person singular verbs for summary DocBlocks in WP_oEmbed.

Also fixes inline @see formatting in appropriate places (summaries should not contain tags or markdown).

Props ramiy.
See #36296.

[DrewAPicture]

In 37069:

Docs: Properly mark $args parameters in two WP_oEmbed methods as optional.

Also clarify that the $args parameters can accept a string (the default) in addition to an array.

Props ramiy.
See #36296.

[swissspidy]

@DrewAPicture Anything else here that needs to be covered?

[DrewAPicture]

@swissspidy Yeah, I think this was probably meant to be closed on 4.5. Closing now. New tickets for any other issues.