dashboards release v3.23.0

Added

• Added Alloy mixin dashboards
• Added Makefile.custom.mk to group scripts usage
  • Added make update-mixin to update mixin dasbhboards
  • Added make lint-dashboards to dashboards linting
  • Added make install-tools to install required tools
• Added scripts/update-alloy-mixin.sh to update the Alloy mixin dashboards
• Added update-alertmanager-mixin and update-kubernetes-mixin Makefile targets

Changed

• Updated all dashboars using decbytes unit to use bytes (IEC units) instead.

Fixed

• Fix dashboards destination path in update-monitoring-mixin-dashboards.sh script