Legal holds, step 1: the hold itself

inbuxa:LegalHold get/set places a hold on accounts, groups, domains,
tenants or the whole server, with an optional date range. A hold's range
and scope can only widen, a released hold is read-only, and none is ever
deleted. Placing, changing and releasing each need a reason and are
audited (LH-1, LH-3, LH-10, AU-12).

Permissions 669-672 (see, place, widen or release, export held data)
go to server administrators only; the tenant ceiling always strips them,
as it does Impersonate (LH-13). Schema: Compliance > Legal Holds.

What a hold keeps comes next, through the undelete hooks.

Also moves the lock expiry helpers below the lock module's imports.

crates/jmap-proto/src/request/mod.rs

@@ -119,6 +119,7 @@ pub enum GetRequestMethod {
     AuditEvent(Box<GetRequest<crate::object::inbuxa_audit::AuditEvent>>),
     AuditSettings(Box<GetRequest<crate::object::inbuxa_audit::AuditSettings>>),
     AccountLock(Box<GetRequest<crate::object::inbuxa_account_lock::AccountLock>>),
+    LegalHold(Box<GetRequest<crate::object::inbuxa_legal_hold::LegalHold>>),
     ProtocolPolicy(Box<GetRequest<crate::object::inbuxa_protocol_policy::ProtocolPolicy>>),
     TenantProtocolPolicy(
         Box<GetRequest<crate::object::inbuxa_tenant_protocol_policy::TenantProtocolPolicy>>,
@@ -151,6 +152,7 @@ pub enum SetRequestMethod<'x> {
     AuditExport(Box<SetRequest<'x, crate::object::inbuxa_audit::AuditExport>>),
     AuditVerification(Box<SetRequest<'x, crate::object::inbuxa_audit::AuditVerification>>),
     AccountLock(Box<SetRequest<'x, crate::object::inbuxa_account_lock::AccountLock>>),
+    LegalHold(Box<SetRequest<'x, crate::object::inbuxa_legal_hold::LegalHold>>),
     ProtocolPolicy(Box<SetRequest<'x, crate::object::inbuxa_protocol_policy::ProtocolPolicy>>),
     TenantProtocolPolicy(
         Box<SetRequest<'x, crate::object::inbuxa_tenant_protocol_policy::TenantProtocolPolicy>>,