chore: move app proxying code to workspaceapps pkg (#6998)

* chore: move app proxying code to workspaceapps pkg

Moves path-app, subdomain-app and reconnecting PTY proxying to the new
workspaceapps.WorkspaceAppServer struct. This is in preparation for
external workspace proxies.

Updates app logout flow to avoid redirecting to coder-logout.${app_host}
on logout. Instead, all subdomain app tokens owned by the logging-out
user will be deleted every time you logout for simplicity sake.

Tests will remain in their original package, pending being moved to an
apptest package (or similar).

Co-authored-by: Steven Masley <stevenmasley@coder.com>

coderd/database/dbfake/databasefake.go

@@ -143,7 +143,7 @@ type data struct {
 	lastUpdateCheck []byte
 	serviceBanner   []byte
 	logoURL         string
-	appSigningKey   string
+	appSecurityKey  string
 	lastLicenseID   int32
 }
 
@@ -679,6 +679,19 @@ func (q *fakeQuerier) DeleteAPIKeyByID(_ context.Context, id string) error {
 	return sql.ErrNoRows
 }
 
+func (q *fakeQuerier) DeleteApplicationConnectAPIKeysByUserID(_ context.Context, userID uuid.UUID) error {
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	for i := len(q.apiKeys) - 1; i >= 0; i-- {
+		if q.apiKeys[i].UserID == userID && q.apiKeys[i].Scope == database.APIKeyScopeApplicationConnect {
+			q.apiKeys = append(q.apiKeys[:i], q.apiKeys[i+1:]...)
+		}
+	}
+
+	return nil
+}
+
 func (q *fakeQuerier) DeleteAPIKeysByUserID(_ context.Context, userID uuid.UUID) error {
 	q.mutex.Lock()
 	defer q.mutex.Unlock()
@@ -4463,18 +4476,18 @@ func (q *fakeQuerier) GetLogoURL(_ context.Context) (string, error) {
 	return q.logoURL, nil
 }
 
-func (q *fakeQuerier) GetAppSigningKey(_ context.Context) (string, error) {
+func (q *fakeQuerier) GetAppSecurityKey(_ context.Context) (string, error) {
 	q.mutex.RLock()
 	defer q.mutex.RUnlock()
 
-	return q.appSigningKey, nil
+	return q.appSecurityKey, nil
 }
 
-func (q *fakeQuerier) InsertAppSigningKey(_ context.Context, data string) error {
+func (q *fakeQuerier) UpsertAppSecurityKey(_ context.Context, data string) error {
 	q.mutex.Lock()
 	defer q.mutex.Unlock()
 
-	q.appSigningKey = data
+	q.appSecurityKey = data
 	return nil
 }