feat(saml): allow setting nameid-format and alternative mapping for transient format (#7979)

# Which Problems Are Solved

ZITADEL currently always uses
`urn:oasis:names:tc:SAML:2.0:nameid-format:persistent` in SAML requests,
relying on the IdP to respect that flag and always return a peristent
nameid in order to be able to map the external user with an existing
user (idp link) in ZITADEL.
In case the IdP however returns a
`urn:oasis:names:tc:SAML:2.0:nameid-format:transient` (transient)
nameid, the attribute will differ between each request and it will not
be possible to match existing users.

# How the Problems Are Solved

This PR adds the following two options on SAML IdP:
- **nameIDFormat**: allows to set the nameid-format used in the SAML
Request
- **transientMappingAttributeName**: allows to set an attribute name,
which will be used instead of the nameid itself in case the returned
nameid-format is transient

# Additional Changes

To reduce impact on current installations, the `idp_templates6_saml`
table is altered with the two added columns by a setup job. New
installations will automatically get the table with the two columns
directly.
All idp unit tests are updated to use `expectEventstore` instead of the
deprecated `eventstoreExpect`.

# Additional Context

Closes #7483
Closes #7743

---------

Co-authored-by: peintnermax <max@caos.ch>
Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

internal/repository/instance/idp.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/repository/idp"
 )
@@ -1016,6 +1017,8 @@ func NewSAMLIDPAddedEvent(
 	certificate []byte,
 	binding string,
 	withSignedRequest bool,
+	nameIDFormat *domain.SAMLNameIDFormat,
+	transientMappingAttributeName string,
 	options idp.Options,
 ) *SAMLIDPAddedEvent {
 	return &SAMLIDPAddedEvent{
@@ -1032,6 +1035,8 @@ func NewSAMLIDPAddedEvent(
 			certificate,
 			binding,
 			withSignedRequest,
+			nameIDFormat,
+			transientMappingAttributeName,
 			options,
 		),
 	}