[Web] Added vnd.dovecot.execute/filter/pipe sieve validator support (fixes #2026) (#4204)

Signed-off-by: Ashus <github.com@ashus.net>

data/web/inc/lib/sieve/extensions/vnd.dovecot.execute.xml

@@ -0,0 +1,17 @@
+<?xml version='1.0' standalone='yes'?>
+
+<extension name="vnd.dovecot.execute">
+
+	<test name="execute">
+		<parameter type="tag" name="pipe" regex="pipe" occurrence="optional"/>
+		<parameter type="string" name="program-name"/>
+		<parameter type="stringlist" name="arguments" occurrence="optional"/>
+	</test>
+
+	<command name="execute">
+		<parameter type="tag" name="pipe" regex="pipe" occurrence="optional"/>
+		<parameter type="string" name="program-name"/>
+		<parameter type="stringlist" name="arguments" occurrence="optional"/>
+	</command>
+	
+</extension>

data/web/inc/lib/sieve/extensions/vnd.dovecot.filter.xml

@@ -0,0 +1,15 @@
+<?xml version='1.0' standalone='yes'?>
+
+<extension name="vnd.dovecot.filter">
+
+	<test name="filter">
+		<parameter type="string" name="program-name"/>
+		<parameter type="stringlist" name="arguments" occurrence="optional"/>
+	</test>
+
+	<command name="filter">
+		<parameter type="string" name="program-name"/>
+		<parameter type="stringlist" name="arguments" occurrence="optional"/>
+	</command>
+
+</extension>

data/web/inc/lib/sieve/extensions/vnd.dovecot.pipe.xml

@@ -0,0 +1,11 @@
+<?xml version='1.0' standalone='yes'?>
+
+<extension name="vnd.dovecot.pipe">
+
+	<command name="pipe">
+		<parameter type="tag" name="try" regex="try" occurrence="optional"/>
+		<parameter type="string" name="program-name"/>
+		<parameter type="stringlist" name="arguments" occurrence="optional"/>
+	</command>
+	
+</extension>