guests/openbsd: Add back `insert_public_key` cap

Copied from linux guest.

plugins/guests/openbsd/cap/insert_public_key.rb

@@ -0,0 +1,21 @@
+require "vagrant/util/shell_quote"
+
+module VagrantPlugins
+  module GuestOpenBSD
+    module Cap
+      class InsertPublicKey
+        def self.insert_public_key(machine, contents)
+          contents = Vagrant::Util::ShellQuote.escape(contents, "'")
+          contents = contents.gsub("\n", "\\n")
+
+          machine.communicate.tap do |comm|
+            comm.execute("mkdir -p ~/.ssh")
+            comm.execute("chmod 0700 ~/.ssh")
+            comm.execute("printf '#{contents}' >> ~/.ssh/authorized_keys")
+            comm.execute("chmod 0600 ~/.ssh/authorized_keys")
+          end
+        end
+      end
+    end
+  end
+end

plugins/guests/openbsd/plugin.rb

@@ -26,6 +26,11 @@ module VagrantPlugins
         Cap::Halt
       end
 
+      guest_capability("openbsd", "insert_public_key") do
+        require_relative "cap/insert_public_key"
+        Cap::InsertPublicKey
+      end
+
       guest_capability("openbsd", "mount_nfs_folder") do
         require_relative "cap/mount_nfs_folder"
         Cap::MountNFSFolder