feat: Add support for GUI sshnp client

[XavierChanth]

- What I did

Arguments:

• Fixed a bunch of merge conflicts related to adding multiple args to SSHNP
  • Added trailing commas to parameter lists to reduce the chances of this kind of merge conflict from reoccurring
• Made legacyDaemon arg optional and provided a default
• Added static const default* arguments to SSHNP class
• Made all port args int type instead of String type

SSHRV:

• Added an abstract class with localBinary and pureDart factory functions
• localBinary runs in a separate process so that CLIs can exit
• pureDart is needed so that the GUI is not dependant on separate binaries elsewhere

Misc:

• Now using part/part of notation for related files
• Added SSHNPResult class, which overrides toString to output the ssh command for CLI, but the class can be intercepted for the GUI

- How I did it

- How to verify it

- Description for the changelog
feat: Add support for GUI sshnp client

[XavierChanth]

Need to merge #366 to fix the rest of the tests