Release 2.1.0

JPERF-218: Enable abstraction of `SshConnection` and all of its publi…

…c methods

Switching from a `class` to an `interface` combined with Kotlin default args causes a binary incompatibility.
The synthetic `$default` bridge methods move from the class itself to a nested static `DefaultImpls` class.
Naturally, existing compiled bytecode still tries to call the old location of the method, causing an `IncompatibleClassChangeError`.
Since it will be a breaking change anyway, this commit pays off the tech debt and removes the default args from `SshConnection` API.

issue/DELTA-553: Add possibility to upload file via SshConnection