net: introduce `Socket#connecting` property
Checklist
-
tests and code linting passes -
a test and/or benchmark is included -
documentation is changed or added -
the commit message follows commit guidelines
Affected core subsystem(s)
net
Description of change
There is no official way to figure out if the socket that you have on
hand is still connecting to the remote host. Introduce
Socket#connecting
, which is essentially an unprefixed _connecting
property that we already had.