feat: new mf_increment macro

tests/base/mf_increment.test.sas

@@ -0,0 +1,35 @@
+/**
+  @file
+  @brief Testing mf_increment macro
+
+  <h4> SAS Macros </h4>
+  @li mf_increment.sas
+  @li mp_assert.sas
+
+**/
+
+%let var=0;
+
+%mp_assert(
+  iftrue=(
+    "%mf_increment(var)"="1"
+  ),
+  desc=Checking basic mf_increment usage 1,
+  outds=work.test_results
+)
+
+%mp_assert(
+  iftrue=(
+    "%mf_increment(var)"="2"
+  ),
+  desc=Checking basic mf_increment usage 2,
+  outds=work.test_results
+)
+
+%mp_assert(
+  iftrue=(
+    "%mf_increment(var,incr=2)"="4"
+  ),
+  desc=Checking incr option,
+  outds=work.test_results
+)