feat: add access control to channels with various modes

- Introduced AccessMode enum to define channel access levels: Public, PasswordProtected, AccountRequired, and OwnerOnly.
- Updated Channel and ProgrammingBlock entities to include access_mode and access_password_hash fields.
- Enhanced create and update channel functionality to handle access mode and password.
- Implemented access checks in channel routes based on the defined access modes.
- Modified frontend components to support channel creation and editing with access control options.
- Added ChannelPasswordModal for handling password input when accessing restricted channels.
- Updated API calls to include channel and block passwords as needed.
- Created database migrations to add access_mode and access_password_hash columns to channels table.

k-tv-backend/migrations_sqlite/20240104000000_add_access_control_to_channels.sql

@@ -0,0 +1,2 @@
+ALTER TABLE channels ADD COLUMN access_mode TEXT NOT NULL DEFAULT 'public';
+ALTER TABLE channels ADD COLUMN access_password_hash TEXT;