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/api/grpc/user/v2/user_integration_test.go

@@ -1883,7 +1883,7 @@ func TestServer_StartIdentityProviderIntent(t *testing.T) {
 	orgResp := Tester.CreateOrganization(IamCTX, fmt.Sprintf("NotDefaultOrg%d", time.Now().UnixNano()), fmt.Sprintf("%d@mouse.com", time.Now().UnixNano()))
 	notDefaultOrgIdpID := Tester.AddOrgGenericOAuthProvider(t, CTX, orgResp.OrganizationId)
 	samlIdpID := Tester.AddSAMLProvider(t, CTX)
-	samlRedirectIdpID := Tester.AddSAMLRedirectProvider(t, CTX)
+	samlRedirectIdpID := Tester.AddSAMLRedirectProvider(t, CTX, "")
 	samlPostIdpID := Tester.AddSAMLPostProvider(t, CTX)
 	type args struct {
 		ctx context.Context