Migrate proxy logic to the API package (#4216)

This allows arbitrary programs to have an easy mechanism to make
connections through Boundary using Go. Internal cluster tests and test
helpers have been migrated to use this package, as well as the `connect`
command.

---------

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

api/proxy/option_test.go

@@ -0,0 +1,89 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package proxy
+
+import (
+	"net"
+	"net/netip"
+	"testing"
+
+	"github.com/hashicorp/boundary/api/targets"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_GetOpts(t *testing.T) {
+	t.Parallel()
+	t.Run("nil", func(t *testing.T) {
+		opts, err := getOpts(nil)
+		require.NoError(t, err)
+		assert.NotNil(t, opts)
+	})
+	t.Run("with-listener", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.Nil(opts.WithListener)
+		_, err = getOpts(WithListener(nil))
+		require.Error(t, err)
+		l := &net.TCPListener{}
+		opts, err = getOpts(WithListener(l))
+		require.NoError(t, err)
+		assert.Equal(l, opts.WithListener)
+	})
+	t.Run("with-listen-addr-port", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.EqualValues(netip.MustParseAddrPort("127.0.0.1:0"), opts.WithListenAddrPort)
+		_, err = getOpts(WithListenAddrPort(netip.AddrPort{}))
+		require.Error(t, err)
+		l := netip.AddrPortFrom(netip.IPv6LinkLocalAllNodes(), 22)
+		opts, err = getOpts(WithListenAddrPort(l))
+		require.NoError(t, err)
+		assert.Equal(l, opts.WithListenAddrPort)
+	})
+	t.Run("with-connections-left-ch", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.Nil(opts.WithConnectionsLeftCh)
+		_, err = getOpts(WithConnectionsLeftCh(nil))
+		require.Error(t, err)
+		l := make(chan int32)
+		opts, err = getOpts(WithConnectionsLeftCh(l))
+		require.NoError(t, err)
+		assert.Equal(l, opts.WithConnectionsLeftCh)
+	})
+	t.Run("with-worker-host", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.Empty(opts.WithWorkerHost)
+		opts, err = getOpts(WithWorkerHost("foo"))
+		require.NoError(t, err)
+		assert.Equal("foo", opts.WithWorkerHost)
+	})
+	t.Run("with-session-authorization-data", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.Nil(opts.WithSessionAuthorizationData)
+		_, err = getOpts(WithSessionAuthorizationData(nil))
+		require.Error(t, err)
+		l := &targets.SessionAuthorizationData{}
+		opts, err = getOpts(WithSessionAuthorizationData(l))
+		require.NoError(t, err)
+		assert.Equal(l, opts.WithSessionAuthorizationData)
+	})
+	t.Run("with-skip-session-teardown", func(t *testing.T) {
+		assert := assert.New(t)
+		opts, err := getOpts()
+		require.NoError(t, err)
+		assert.Empty(opts.WithSkipSessionTeardown)
+		opts, err = getOpts(WithSkipSessionTeardown(true))
+		require.NoError(t, err)
+		assert.True(opts.WithSkipSessionTeardown)
+	})
+}