feat(rt): IDP Intents Relational Table (#11374)

# Which Problems Are Solved

In the context of moving our datastore to relational tables, Identity
Provider Intents have no definition of a relational table nor any DB API
that can be used to store the IDP intents as relational objects.

# How the Problems Are Solved

The PR follows the guidelines left in #11190

- A table `zitadel.identity_provider_intents` is created: it defines its
relational constraints (foreign keys) with the other tables, as well as
an ENUM to represent the state of the intent.
- An IDP Intent repository has been created, which offers CRUD
operations implemented as `Create`, `Get`, `Update` and `Delete` methods
for the IDP intent.
- The repository also defines all columns and conditions useful for
performing DB operations on the IDP intents.
- DB mocks have been added as well to ease testing on the `domain`
package.
- Reduction functions have been implemented for the existing IDP events
so to keep the relational table in sync with the event store.

# Additional Changes

To allow testing LDAP intent flow, the `Session.FetchUser()` method has
been extracted to a separate file. A corresponding mock has been created
as well in `fetch_user_mock.go`. The files are mutually excluded and
added at build time through go build tags: the mock is added when the
`integration` tag is specified, while the real implementation is added
when the same tag IS NOT added to the build tags.

# Additional Context

- Closes #11190

---------

Co-authored-by: Livio Spring <[email protected]>
Co-authored-by: Silvan <[email protected]>

backend/v3/storage/database/dialect/postgres/migration/012_identity_provider_intents_table.go

@@ -0,0 +1,16 @@
+package migration
+
+import (
+	_ "embed"
+)
+
+var (
+	//go:embed 012_identity_provider_intents_table/up.sql
+	up012IDPIntentsTable string
+	//go:embed 012_identity_provider_intents_table/down.sql
+	down012IDPIntentsTable string
+)
+
+func init() {
+	registerSQLMigration(12, up012IDPIntentsTable, down012IDPIntentsTable)
+}

backend/v3/storage/database/dialect/postgres/migration/012_identity_provider_intents_table/down.sql

@@ -0,0 +1,2 @@
+DROP TABLE IF EXISTS zitadel.identity_provider_intents;
+DROP TYPE IF EXISTS zitadel.idp_intent_state;

backend/v3/storage/database/dialect/postgres/migration/012_identity_provider_intents_table/up.sql

@@ -0,0 +1,44 @@
+CREATE TYPE zitadel.idp_intent_state AS ENUM (
+    'started',
+    'succeeded',
+    'failed',
+    'consumed'
+    );
+
+CREATE TABLE zitadel.identity_provider_intents
+(
+    instance_id             TEXT                        NOT NULL,
+    id                      TEXT                        NOT NULL CHECK ( id <> '' ),
+    state                   zitadel.idp_intent_state    NOT NULL DEFAULT 'started',
+    success_url             TEXT,
+    failure_url             TEXT,
+    created_at              TIMESTAMPTZ                 NOT NULL DEFAULT NOW(),
+    updated_at              TIMESTAMPTZ                 NOT NULL DEFAULT NOW(),
+    idp_id                  TEXT                        NOT NULL,
+    idp_arguments           JSONB,
+    idp_user                BYTEA, 
+    idp_user_id             TEXT,
+    idp_username            TEXT,
+    user_id                 TEXT,
+    idp_access_token        JSONB,
+    idp_id_token            TEXT,
+    idp_entry_attributes    JSONB,
+    request_id              TEXT,
+    assertion               JSONB,
+    succeeded_at            TIMESTAMPTZ,
+    fail_reason             TEXT,
+    failed_at               TIMESTAMPTZ,
+    expires_at              TIMESTAMPTZ,
+
+    PRIMARY KEY (instance_id, id),
+    -- TODO(@adlerhurst): easiest would be to create the index in the user migrations so that we can merge this one but the problem is that the migration might fail if there are already intents created.
+    -- FOREIGN KEY (instance_id, user_id) REFERENCES zitadel.users (instance_id, id) ON DELETE CASCADE,
+    FOREIGN KEY (instance_id, idp_id) REFERENCES zitadel.identity_providers (instance_id, id) ON DELETE CASCADE
+);
+
+CREATE TRIGGER trigger_set_updated_at
+    BEFORE UPDATE
+    ON zitadel.identity_provider_intents
+    FOR EACH ROW
+    WHEN (NEW.updated_at IS NULL)
+EXECUTE FUNCTION zitadel.set_updated_at();