Clean up obsolete version constraints

[chrismarget-j]

This PR cleans up obsolete version constraints.

Obsolete here means two things:

• incompatible with Apstra's semver behavior
• constraints revolving around Apstra 4.1 (for which we've dropped support)

Changes in this PR:

• eliminate old version constraints in apstra/api_versions/constraints.go
  • these used hashicorp's strict semver package
  • required introduction of FabricSettingsSetInCreate using our non-semver constraint package
• eliminate 4.1.x constants
• eliminate references to 4.1.x in documentation
  • one reference remains
  • it's been converted from a constant to a string
  • that string will be eliminated by Remove obsolete fabric_link_addressing attribute from template resources/data sources #929
• eliminate 4.1.x constraints in test cases
• eliminate 4.1.x-only test cases

Tested with:

• 4.2.0
• 4.2.1
• 4.2.1.1
• 4.2.2
• 5.0.0