feat: add incus auto-client certificate trust (#406)

- add fact to export vault public cert from agents
- add fact to export list of trusted incus client certs
- add method for incus clients to export their client cert to be trusted

Reviewed-on: #406

modules/incus/lib/facter/incus_trust_list.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# lib/facter/incus_trust_list.rb
+require 'json'
+
+Facter.add(:incus_trust_list) do
+  confine do
+    # Only run on systems that have incus installed and running
+    incus_path = Facter::Util::Resolution.which('incus')
+    incus_path && File.exist?('/var/lib/incus/server.key')
+  end
+
+  setcode do
+    incus_path = Facter::Util::Resolution.which('incus')
+    next {} unless incus_path
+
+    begin
+      # Run incus config trust list --format=json
+      trust_output = Facter::Core::Execution.execute("#{incus_path} config trust list --format=json")
+      next {} if trust_output.empty?
+
+      # Parse the JSON output
+      JSON.parse(trust_output)
+    rescue StandardError
+      {}
+    end
+  end
+end