Front-end integration for disabled subservers

[itsrachelfish]

This PR creates a new SubServerStatus store which checks which services are being run by litd. When loop and pool are not running or are in an error state, the page displays an error message:

Depends on #541

[jbrill]

Also for the svg, we might want to tweak the color to be fill="currentColor" instead of fill="none"

[dstrukt]

ACK to @jbrill's SVG comment! Always have to remember that one when dealing with icons 😂

[lightninglabs-deploy]

@jbrill: review reminder @itsrachelfish, remember to re-request review from reviewers when ready