fix(login): improve auth handlers (#7969)

# Which Problems Are Solved

During the implementation of #7486 it was noticed, that projections in
the `auth` database schema could be blocked.
Investigations suggested, that this is due to the use of
[GORM](https://gorm.io/index.html) and it's inability to use an existing
(sql) transaction.
With the improved / simplified handling (see below) there should also be
a minimal improvement in performance, resp. reduced database update
statements.

# How the Problems Are Solved

The handlers in `auth` are exchanged to proper (sql) statements and gorm
usage is removed for any writing part.
To further improve / simplify the handling of the users, a new
`auth.users3` table is created, where only attributes are handled, which
are not yet available from the `projections.users`,
`projections.login_name` and `projections.user_auth_methods` do not
provide. This reduces the events handled in that specific handler by a
lot.

# Additional Changes

None

# Additional Context

relates to #7486

cmd/setup/26.sql

@@ -0,0 +1,16 @@
+CREATE TABLE IF NOT EXISTS auth.users3 (
+    instance_id TEXT NOT NULL,
+    id TEXT NOT NULL,
+    resource_owner TEXT NOT NULL,
+    change_date TIMESTAMPTZ NULL,
+    password_set BOOL NULL,
+    password_change TIMESTAMPTZ NULL,
+    last_login TIMESTAMPTZ NULL,
+    init_required BOOL NULL,
+    mfa_init_skipped TIMESTAMPTZ NULL,
+    username_change_required BOOL NULL,
+    passwordless_init_required BOOL NULL,
+    password_init_required BOOL NULL,
+
+    PRIMARY KEY (instance_id, id)
+)