mqtt: Move from policy/ into base/

Register dpd signatures and the analyzer when running in default mode.

Closes #2583

scripts/base/protocols/mqtt/README

@@ -1 +1 @@
-Definitions of constants used by the MQTT protocol
+Support for MQTT protocol analysis.

scripts/base/protocols/mqtt/__load__.zeek

@@ -1 +1,4 @@
 @load ./consts
+@load ./main
+
+@load-sigs ./dpd.sig

scripts/policy/protocols/mqtt/README

@@ -1 +0,0 @@
-Support for MQTT protocol analysis.

scripts/policy/protocols/mqtt/__load__.zeek

@@ -1,2 +1,4 @@
-@load ./main
-@load-sigs ./dpd.sig
+@deprecated "Remove in v6.1. The MQTT scripts have been moved out of policy/ into base and are loaded by default"
+
+# For those running bare-mode and loading protocols/mqtt from policy.
+@load base/protocols/mqtt

scripts/test-all-policy.zeek

@@ -110,8 +110,7 @@
 @load protocols/krb/ticket-logging.zeek
 @load protocols/modbus/known-masters-slaves.zeek
 @load protocols/modbus/track-memmap.zeek
-@load protocols/mqtt/__load__.zeek
-@load protocols/mqtt/main.zeek
+#@load protocols/mqtt/__load__.zeek
 @load protocols/mysql/software.zeek
 @load protocols/rdp/indicate_ssl.zeek
 @load protocols/smb/log-cmds.zeek

scripts/zeekygen/__load__.zeek

@@ -1,6 +1,7 @@
 @load test-all-policy.zeek
 
 # Scripts which are commented out in test-all-policy.zeek.
+@load protocols/mqtt/__load__.zeek
 @load protocols/ssl/decryption.zeek
 @load frameworks/control/controllee.zeek
 @load frameworks/control/controller.zeek