Split lock and connection setup

Allow run the pre-connect hook before the first SSH command is executed,
but only run the locking in `with_lock` blocks.

test/cli/main_test.rb

@@ -92,6 +92,9 @@ class CliMainTest < CliTestCase
   test "deploy when locked" do
     Thread.report_on_exception = false
 
+    SSHKit::Backend::Abstract.any_instance.stubs(:execute)
+    Dir.stubs(:chdir)
+
     SSHKit::Backend::Abstract.any_instance.stubs(:execute)
       .with { |*args| args == [ :mkdir, "-p", ".kamal" ] }
 
@@ -113,6 +116,9 @@ class CliMainTest < CliTestCase
   test "deploy error when locking" do
     Thread.report_on_exception = false
 
+    SSHKit::Backend::Abstract.any_instance.stubs(:execute)
+    Dir.stubs(:chdir)
+
     SSHKit::Backend::Abstract.any_instance.stubs(:execute)
       .with { |*args| args == [ :mkdir, "-p", ".kamal" ] }