Give IMAP, POP3 and ManageSieve a switch each

The legacy-protocols switch was all or nothing. An operator can now stop
POP3 and keep IMAP: each of IMAP, POP3 and ManageSieve has its own
switch, server-wide on inbuxa:ProtocolPolicy and per tenant on
inbuxa:TenantProtocolPolicy (properties imap, pop3, manageSieve).

legacyProtocols stays as the kill-all: setting it sets all three, and it
reads "disabled" exactly when all three are off. A policy stored before
this has only legacyProtocols and reads as all three at that value, so
existing servers and tenants carry over unchanged. In one /set, a
protocol named beside legacyProtocols overrides it.

SMTP submission keeps no switch of its own: sign-in over it is refused
only when all three are off, as the single switch did (LP-6), so
turning one protocol off never stops a mail app sending. For a tenant,
the server's switches and the tenant's count together.

Server-wide, a change closes the listeners of whatever is now off and
puts back the saved listeners of whatever is on again, both in one
change if asked; listeners of a protocol still off stay saved. Sign-in,
autoconfig, autodiscover, PACC (now prepared once per combination) and
the suggested DNS records all follow each protocol separately. A tenant
may turn a protocol on only while the server has it on (LP-9), and the
refusal names which. The JMAP session adds legacyAllowed, the protocols
still allowed for the account; legacyProtocols there keeps its meaning
for older webmail builds. Events name the switches ("pop3 disabled"),
and audit before/after reads every switch even from an older policy.

Tested: unit tests for the switches, the old-policy reading, the
server/tenant combination, the tenant refusal and listener refusal; and
tests/e2e/legacy_protocols.py against a running server, all 100 checks,
including new ones: POP3 alone off closes only its port and refuses
only its sign-in while IMAP and sending go on; only POP3 stops being
advertised; one change closes IMAP and reopens POP3; a tenant turns
POP3 off for itself, and can't turn IMAP on while the server has it off.

crates/common/src/network/autoconfig/legacy_autoconfig.rs

@@ -6,7 +6,7 @@
  * Modified by Coffey Labs in 2026 for INBUXA.
  */
 
-use crate::{Server, manager::application::Resource, network::legacy::is_legacy_service};
+use crate::{Server, manager::application::Resource};
 use registry::schema::enums::ServiceProtocol;
 use std::fmt::Write;
 use utils::url_params::UrlParams;
@@ -31,7 +31,7 @@ impl Server {
         };
 
         // inbuxa: legacy-protocols LP-7, LP-14a
-        let legacy_off = self.legacy_protocols_off_for(domain).await?;
+        let legacy_off = self.legacy_off_for(domain).await?;
 
         // Build XML response
         let mut config = String::with_capacity(1024);
@@ -45,7 +45,7 @@ impl Server {
             "\t\t<displayShortName>{domain}</displayShortName>"
         );
         for (protocol, service) in &self.core.network.info.services {
-            if legacy_off && is_legacy_service(protocol) {
+            if legacy_off.service(protocol) {
                 continue;
             }
             let (protocol, tag, ports) = match protocol {