Allow arbitrary sshOptions to be passed to ssh2

[steverice]

This allows for an arbitrary sshOptions to be passed in Modem options and be used when passed to the ssh constructor to get an agent from the ssh2 library.

This is a breaking change as some previous options are no longer supported.

Effectively reverts b565f55, d2f92b2, and part of 05f4319.

[steverice]

As discussed in #119 (comment), this is a breaking change that will require a major version bump.

[HorusGoul]

Can't we keep and deprecate the old config alongside the new sshOptions config to avoid a major version bump right now? Also is there anything blocking this PR? I could probably help if it's related to development. @apocas @steverice

Thanks!

[iammathew]

Hey,
Is there anything here to do to help move this PR along? Would be willing to help out :)

[apocas]

Tackling this tonight.

[apocas]

Can't we keep and deprecate the old config alongside the new sshOptions config to avoid a major version bump right now? Also is there anything blocking this PR? I could probably help if it's related to development. @apocas @steverice

Thanks!

I don't see why we need to do a major bump with this. Retro-compatibility is maintained.