add perf test for decimal aggregates

dbms/tests/performance/decimal_aggregates.xml

+<test>
+    <type>loop</type>
+
+    <create_query>CREATE TABLE t (x UInt64, d32 Decimal32(3), d64 Decimal64(4), d128 Decimal128(5)) ENGINE = Memory</create_query>
+    <fill_query>INSERT INTO t SELECT number AS x, x AS d32, x AS d64, x d128 FROM numbers(1000000)</fill_query>
+    <drop_query>DROP TABLE IF EXISTS t</drop_query>
+
+    <stop_conditions>
+        <all_of>
+            <iterations>10</iterations>
+        </all_of>
+    </stop_conditions>
+
+    <main_metric>
+        <rows_per_second />
+    </main_metric>
+
+    <query>SELECT min(d32), max(d32), argMin(x, d32), argMax(x, d32) FROM t</query>
+    <query>SELECT min(d64), max(d64), argMin(x, d64), argMax(x, d64) FROM t</query>
+    <query>SELECT min(d128), max(d128), argMin(x, d128), argMax(x, d128) FROM t</query>
+    
+    <query>SELECT avg(d32), sum(d32), sumWithOverflow(d32) FROM t</query>
+    <query>SELECT avg(d64), sum(d64), sumWithOverflow(d64) FROM t</query>
+    <query>SELECT avg(d128), sum(d128), sumWithOverflow(d128) FROM t</query>
+
+    <query>SELECT uniq(d32), uniqCombined(d32), uniqExact(d32), uniqHLL12(d32) FROM t</query>
+    <query>SELECT uniq(d64), uniqCombined(d64), uniqExact(d64), uniqHLL12(d64) FROM t</query>
+    <query>SELECT uniq(d128), uniqCombined(d128), uniqExact(d128), uniqHLL12(d128) FROM t</query>
+    
+    <query>SELECT median(d32), medianExact(d32), medianExactWeighted(d32, 2) FROM t</query>
+    <query>SELECT median(d64), medianExact(d64), medianExactWeighted(d64, 2) FROM t</query>
+    <query>SELECT median(d128), medianExact(d128), medianExactWeighted(d128, 2) FROM t</query>
+    
+    <query>SELECT quantile(d32), quantileExact(d32), quantileExactWeighted(d32, 2) FROM t</query>
+    <query>SELECT quantile(d64), quantileExact(d64), quantileExactWeighted(d64, 2) FROM t</query>
+    <query>SELECT quantile(d128), quantileExact(d128), quantileExactWeighted(d128, 2) FROM t</query>
+
+    <query>SELECT quantilesExact(0.1, 0.9)(d32), quantilesExactWeighted(0.1, 0.9)(d32, 2) FROM t</query>
+    <query>SELECT quantilesExact(0.1, 0.9)(d64), quantilesExactWeighted(0.1, 0.9)(d64, 2) FROM t</query>
+    <query>SELECT quantilesExact(0.1, 0.9)(d128), quantilesExactWeighted(0.1, 0.9)(d128, 2) FROM t</query>
+    
+    <query>SELECT varPop(d32), varSamp(d32), stddevPop(d32) FROM t</query>
+    <query>SELECT varPop(d64), varSamp(d64), stddevPop(d64) FROM t</query>
+    <query>SELECT varPop(d128), varSamp(d128), stddevPop(d128) FROM t</query>
+</test>