doc: tls: added path property to tls.connect

In tls.connect a unix socket connection to a path may be made in
recent versions of node by specifying the value for the path
property.

Signed-off-by: Fedor Indutny <fedor@indutny.com>
deps: provide TXT chunk info in c-ares

Provide more information in `ares_txt_reply` to coalesce chunks from the
same record into one string.

fix #7367
http: add request.flush() method

Forcibly flushes the request headers.  You need this with long-lived
HTTP connections where the first data isn't written until the connection
has been established (think: tunneling requests over HTTP CONNECT.)

Fixes #7296.

Signed-off-by: Fedor Indutny <fedor@indutny.com>