Before this PR, config parsing would accept duplicate job names.
`zrepl daemon` would later fail to start with a panic.
But tools like `zrepl configcheck` would pass.
This PR adds a check to ensure job names are unique.
Similarly, internal job names were not being rejected by config
parsing
Move that check to parse-time as well.
While investigating https://github.com/zrepl/zrepl/issues/700
I checked in on `zrepl status` dependencies and found that
`cview`, which was/is a fork of tview, appears to be unmaintained.
We switched to it 4.5 years ago in a58ce74.
Checking now, `github.com/rivo/tview` seems to be somewhat maintained
again.
I also checked what k9s uses because that tool came to mind as a Go
terminal UI app.
It does use `tview`, but, a fork that has diverged substantially.
Maybe in another 4.5 years stuff the ecosystem has consolidated...
refs https://github.com/zrepl/zrepl/issues/700
Christian Schwarz