Add some target fields and move some things around (#3879)

In preparation for putting proxy code in the api package this creates some necessary fields in the target output and it pre-moves credential parsing and proxy handshake code to their new places. This will make the diff for the actual proxy code move quite a bit smaller.

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

internal/tests/api/credentials/credentials_test.go

@@ -495,7 +495,7 @@ func TestUpdateAfterKeyRotation(t *testing.T) {
 	// Should start asynchronous rewrapping of the encrypted JSON credential
 	assert.Equal("pending", result.State)
 
-	ctx, cancel := context.WithTimeout(ctx, time.Minute)
+	ctx, cancel := context.WithTimeout(ctx, 3*time.Minute)
 	defer cancel()
 	for {
 		jobs, err := scopesClient.ListKeyVersionDestructionJobs(ctx, proj.PublicId)

internal/tests/helper/testing_helper.go

@@ -22,9 +22,9 @@ import (
 	"github.com/hashicorp/boundary/internal/cmd/commands/connect"
 	"github.com/hashicorp/boundary/internal/daemon/controller/common"
 	"github.com/hashicorp/boundary/internal/daemon/worker"
-	"github.com/hashicorp/boundary/internal/proxy"
 	"github.com/hashicorp/boundary/internal/session"
 	targetspb "github.com/hashicorp/boundary/sdk/pbs/controller/api/resources/targets"
+	"github.com/hashicorp/boundary/sdk/pbs/proxy"
 	"github.com/hashicorp/go-cleanhttp"
 	"github.com/hashicorp/go-secure-stdlib/base62"
 	"github.com/mr-tron/base58"
@@ -333,8 +333,8 @@ type TestSessionConnection struct {
 }
 
 // Close a test connection
-func (t *TestSessionConnection) Close() error {
-	return t.conn.Close()
+func (c *TestSessionConnection) Close() error {
+	return c.conn.Close()
 }
 
 // Connect returns a TestSessionConnection for a TestSession. Check