fix: update resetoption and adding test

tests/crossplatform/mp_resetoption.test.sas

@@ -0,0 +1,31 @@
+/**
+  @file
+  @brief Testing mp_resetoption macro
+
+  <h4> SAS Macros </h4>
+  @li mp_assert.sas
+  @li mp_assertscope.sas
+  @li mp_resetoption.sas
+
+**/
+
+
+%let orig=%sysfunc(getoption(obs));
+
+options obs=30;
+
+%mp_assertscope(SNAPSHOT)
+%mp_resetoption(OBS)
+%mp_assertscope(COMPARE)
+
+%let new=%sysfunc(ifc(
+  "%substr(&sysver,1,1)" ne "4" and "%substr(&sysver,1,1)" ne "5",
+  %sysfunc(getoption(obs)), /* test it worked */
+  &orig /* cannot test as option unavailable */
+));
+
+%mp_assert(
+  iftrue=(&new=&orig),
+  desc=Checking option was reset (if reset option available),
+  outds=work.test_results
+)