Allow multiple arguments for exec commands

If you can have an alias like:

```
aliases:
  rails: app exec -p rails
```

Then `kamal rails db:migrate:status` will execute
`kamal app exec -p rails db:migrate:status`.

So this works, we'll allow multiple arguments `app exec` and
`server exec` to accept multiple arguments.

The arguments are combined by simply joining them with a space. This
means that these are equivalent:

```
kamal app exec -p rails db:migrate:status
kamal app exec -p "rails db:migrate:status"
```

If you want to pass an argument with spaces, you'll need to quote it:

```
kamal app exec -p "git commit -am \"My comment\""
kamal app exec -p git commit -am "\"My comment\""
```

test/cli/app_test.rb

@@ -247,6 +247,12 @@ class CliAppTest < CliTestCase
     end
   end
 
+  test "exec separate arguments" do
+    run_command("exec", "ruby", " -v").tap do |output|
+      assert_match "docker run --rm --env-file .kamal/env/roles/app-web.env dhh/app:latest ruby -v", output
+    end
+  end
+
   test "exec with reuse" do
     run_command("exec", "--reuse", "ruby -v").tap do |output|
       assert_match "sh -c 'docker ps --latest --format '\\''{{.Names}}'\\'' --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting --filter ancestor=$(docker image ls --filter reference=dhh/app:latest --format '\\''{{.ID}}'\\'') ; docker ps --latest --format '\\''{{.Names}}'\\'' --filter label=service=app --filter label=role=web --filter status=running --filter status=restarting' | head -1 | while read line; do echo ${line#app-web-}; done", output # Get current version

test/cli/main_test.rb

@@ -566,6 +566,13 @@ class CliMainTest < CliTestCase
     end
   end
 
+  test "append to command with an alias" do
+    run_command("rails", "db:migrate:status", config_file: "deploy_with_aliases").tap do |output|
+      assert_match "docker exec app-console-999 rails db:migrate:status on 1.1.1.5", output
+      assert_match "App Host: 1.1.1.5", output
+    end
+  end
+
   private
     def run_command(*command, config_file: "deploy_simple")
       with_argv([ *command, "-c", "test/fixtures/#{config_file}.yml" ]) do

test/cli/server_test.rb

@@ -3,8 +3,8 @@ require_relative "cli_test_case"
 class CliServerTest < CliTestCase
   test "running a command with exec" do
     SSHKit::Backend::Abstract.any_instance.stubs(:capture)
-    .with("date", verbosity: 1)
-    .returns("Today")
+      .with("date", verbosity: 1)
+      .returns("Today")
 
     hosts = "1.1.1.1".."1.1.1.4"
     run_command("exec", "date").tap do |output|
@@ -15,6 +15,20 @@ class CliServerTest < CliTestCase
     end
   end
 
+  test "running a command with exec multiple arguments" do
+    SSHKit::Backend::Abstract.any_instance.stubs(:capture)
+      .with("date -j", verbosity: 1)
+      .returns("Today")
+
+    hosts = "1.1.1.1".."1.1.1.4"
+    run_command("exec", "date", "-j").tap do |output|
+      hosts.map do |host|
+        assert_match "Running 'date -j' on #{hosts.to_a.join(', ')}...", output
+        assert_match "App Host: #{host}\nToday", output
+      end
+    end
+  end
+
   test "bootstrap already installed" do
     stub_setup
     SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:docker, "-v", raise_on_non_zero_exit: false).returns(true).at_least_once