feat(backend): state persisted objects (#9870)

This PR initiates the rework of Zitadel's backend to state-persisted
objects. This change is a step towards a more scalable and maintainable
architecture.

## Changes

* **New `/backend/v3` package**: A new package structure has been
introduced to house the reworked backend logic. This includes:
* `domain`: Contains the core business logic, commands, and repository
interfaces.
* `storage`: Implements the repository interfaces for database
interactions with new transactional tables.
  * `telemetry`: Provides logging and tracing capabilities.
* **Transactional Tables**: New database tables have been defined for
`instances`, `instance_domains`, `organizations`, and `org_domains`.
* **Projections**: New projections have been created to populate the new
relational tables from the existing event store, ensuring data
consistency during the migration.
* **Repositories**: New repositories provide an abstraction layer for
accessing and manipulating the data in the new tables.
* **Setup**: A new setup step for `TransactionalTables` has been added
to manage the database migrations for the new tables.

This PR lays the foundation for future work to fully transition to
state-persisted objects for these components, which will improve
performance and simplify data access patterns.

This PR initiates the rework of ZITADEL's backend to state-persisted
objects. This is a foundational step towards a new architecture that
will improve performance and maintainability.

The following objects are migrated from event-sourced aggregates to
state-persisted objects:

* Instances
  * incl. Domains
* Orgs
  * incl. Domains

The structure of the new backend implementation follows the software
architecture defined in this [wiki
page](https://github.com/zitadel/zitadel/wiki/Software-Architecturel).

This PR includes:

* The initial implementation of the new transactional repositories for
the objects listed above.
* Projections to populate the new relational tables from the existing
event store.
* Adjustments to the build and test process to accommodate the new
backend structure.

This is a work in progress and further changes will be made to complete
the migration.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Iraq Jaber <iraq+github@zitadel.com>
Co-authored-by: Iraq <66622793+kkrime@users.noreply.github.com>
Co-authored-by: Tim Möhlmann <tim+github@zitadel.com>

backend/v3/storage/database/repository/user_machine.go

@@ -0,0 +1,67 @@
+package repository
+
+import (
+	"context"
+
+	"github.com/zitadel/zitadel/backend/v3/domain"
+	"github.com/zitadel/zitadel/backend/v3/storage/database"
+)
+
+type userMachine struct {
+	*user
+}
+
+var _ domain.MachineRepository = (*userMachine)(nil)
+
+// -------------------------------------------------------------
+// repository
+// -------------------------------------------------------------
+
+// Update implements [domain.MachineRepository].
+func (m userMachine) Update(ctx context.Context, condition database.Condition, changes ...database.Change) error {
+	builder := database.StatementBuilder{}
+	builder.WriteString("UPDATE user_machines SET ")
+	database.Changes(changes).Write(&builder)
+	writeCondition(&builder, condition)
+	m.writeReturning()
+
+	_, err := m.client.Exec(ctx, builder.String(), builder.Args()...)
+	return err
+}
+
+// -------------------------------------------------------------
+// changes
+// -------------------------------------------------------------
+
+// SetDescription implements [domain.machineChanges].
+func (m userMachine) SetDescription(description string) database.Change {
+	return database.NewChange(m.DescriptionColumn(), description)
+}
+
+// -------------------------------------------------------------
+// conditions
+// -------------------------------------------------------------
+
+// DescriptionCondition implements [domain.machineConditions].
+func (m userMachine) DescriptionCondition(op database.TextOperation, description string) database.Condition {
+	return database.NewTextCondition(m.DescriptionColumn(), op, description)
+}
+
+// -------------------------------------------------------------
+// columns
+// -------------------------------------------------------------
+
+// DescriptionColumn implements [domain.machineColumns].
+func (m userMachine) DescriptionColumn() database.Column {
+	return database.NewColumn("user_machines", "description")
+}
+
+func (m userMachine) columns() database.Columns {
+	return append(m.user.columns(), m.DescriptionColumn())
+}
+
+func (m *userMachine) writeReturning() {
+	builder := database.StatementBuilder{}
+	builder.WriteString(" RETURNING ")
+	m.columns().WriteQualified(&builder)
+}