Import upstream v0.16.22, stripped

Upstream commit: 474dd0229cb20cf513036619781ed97bd8073c3f
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 117 in 50 files
Dangling module declarations removed: 5
Cargo edits turning enterprise off: 14
Verification: clean
Enterprise feature gates left for rebuilt features: 19 in 18 files

Produced by tools/fork/strip.py. The full report is in docs/fork/strip-reports/ on main.

resources/systemd/stalwart.mail.plist

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
+    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+    <dict>
+        <key>Label</key>
+        <string>stalwart.mail</string>
+        <key>ServiceDescription</key>
+        <string>Stalwart</string>
+        <key>ProgramArguments</key>
+        <array>
+            <string>__PATH__/bin/stalwart</string>
+            <string>--config=__PATH__/etc/config.json</string>
+        </array>
+        <key>RunAtLoad</key>
+        <true/>
+        <key>KeepAlive</key>
+        <true/>
+    </dict>
+</plist>