app/vmctl: vm-native - split migration on per-metric basis
`vm-native` mode now splits the migration process on per-metric basis.
This allows to migrate metrics one-by-one according to the specified filter.
This change allows to retry export/import requests for a specific metric and provides a better
understanding of the migration progress.
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
vmctl: fix vmctl blocking on process interrupt
This change prevents vmctl from indefinite blocking on
receiving the interrupt signal. The update touches all
import modes and suppose to improve tool reliability.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2491
