Attempt to fix the slow startup some people are having by using the vim/neovim job apis

[blankname]

Attempt the solution proposed by @chemzqm in dag#34 (comment)

If someone could test it using vim on windows and let me know if it works that'd be great.

Vim's documentation for job_start seems to suggest that we might need to use a String for {command} on windows and a List on unix:

I'm not sure if this should be merged as the cause of the slowness might just be misconfiguration of fish (such as using set fish_user_paths $fish_user_paths /new/path in their config.fish, which will cause fish_user_paths to grow each time fish is started).

[blankname]

The instances of slow startup seem to be caused by configuration issues.

The best fix for users is to fix their fish configuration.

This being the case the job API use is complication without benefit.