WP_HTTP HTTP/1.1 needs to send Connection Close + support Transfer-encoding better

[dd32]

WP_HTTP accepts a 'httpversion' argument, and supports some functions of it (such as Transfer-encoding).

However, there are 2 things which are rather broken

1. It doesn't send a Connection: close header, so the connection is held open and WP_HTTP never returns
2. Transfer-Encoding: chunked appears to be rather broken, causing it to returning the end of the document rather than the decoded document.

The attached patch goes some of the way towards making that work better, but is mostly untested, and could do with a unit test or two.

[dd32]

In 25150:

WP_HTTP: When requesting a document with HTTP/1.1 include the 'Connection: Close' header (unless a Connection header is already specified) to prevent the connection being held open and hanging the request process. See #23463

[dd32]

In 25153:

WP_HTTP: Improve WP_HTTP::chunkTransferDecode() to properly handle binary data and chunked responses which include data in the page that looks like a chunked response.
This also fixes a case where the gzip'd data would become corrupt after chunked decoding as \r\n was replaced with \n in the data stream. Fixes #23463

[dd32]

In 25155:

WP_HTTP: Fix a variable typo in [25153] See #23463