migration: T6006: add system component version to config.boot.default by separating activation from migration

[jestabro]

Change Summary

NOTE: required companion PR's:
vyos-build: vyos/vyos-build#651
vyatta-op: vyos/vyatta-op#91

Distinguish activation-scripts from migration-scripts, to avoid migration of config.boot.default on installation and its attendant problems. The organization here may be subsumed into other ongoing development, but the explicit distinction is recommended to resolve open issues and delimit the issue.

The original problem: config settings were either introduced when undesirable, or missed when applicable, dependent on the effects of specific migration scripts. For example:

migration-scripts/conntrack/2-to-3: adds back in conntrack modules after dropping disable boolean value
migration-scripts/interfaces/20-to-21: detects and adds offload settings, when supported by the system

The former may not be desired, but will automatically be added if config.boot.default has component version conntrack < 3; the latter is desired, but unavailable if component version interfaces > 20.

Making the distinction activate/migrate and installing current system versions to config.boot.default resolves these issues, and provides a model going forward.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T6447

Related PR(s)

vyos/vyos-build#651
vyos/vyatta-op#91

Component(s) name

Proposed changes

How to test

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly