fix: relax parsing of SCIM user 'active' flag to improve compatibility (#9296)

# Which Problems Are Solved
- Microsoft Entra invokes the user patch endpoint with `"active":
"True"` / `"active": "False"` when patching a user. This is a well-known
bug in MS Entra (see
[here](https://learn.microsoft.com/en-us/entra/identity/app-provisioning/application-provisioning-config-problem-scim-compatibility)),
but the bug fix has not landed yet and/or the feature flag does not
work.

# How the Problems Are Solved
- To ensure compatibility with MS Entra, the parsing of the the boolean
active flag of the scim user is relaxed and accepts strings in any
casing that resolve to `true` or `false` as well as raw boolean values.

# Additional Context
Part of https://github.com/zitadel/zitadel/issues/8140

internal/api/scim/resources/user.go

@@ -39,7 +39,7 @@ type ScimUser struct {
 	PreferredLanguage      language.Tag                  `json:"preferredLanguage,omitempty"`
 	Locale                 string                        `json:"locale,omitempty"`
 	Timezone               string                        `json:"timezone,omitempty"`
-	Active                 *bool                         `json:"active,omitempty"`
+	Active                 *scim_schemas.RelaxedBool     `json:"active,omitempty"`
 	Emails                 []*ScimEmail                  `json:"emails,omitempty" scim:"required"`
 	PhoneNumbers           []*ScimPhoneNumber            `json:"phoneNumbers,omitempty"`
 	Password               *scim_schemas.WriteOnlyString `json:"password,omitempty"`