feat: adding new mf_deletefile macro (and test)

Also, update to mm_spkexport macro

base/mf_deletefile.sas

@@ -0,0 +1,31 @@
+/**
+  @file
+  @brief Deletes a physical file, if it exists
+  @details Usage:
+
+      %mf_writefile(&sasjswork/myfile.txt,l1=some content)
+
+      %mf_deletefile(&sasjswork/myfile.txt)
+
+      %mf_deletefile(&sasjswork/myfile.txt)
+
+
+  @param filepath Full path to the target file
+
+  @returns The return code from the fdelete() invocation
+
+  <h4> Related Macros </h4>
+  @li mf_deletefile.test.sas
+  @li mf_writefile.sas
+
+  @version 9.2
+  @author Allan Bowe
+**/
+
+%macro mf_deletefile(file
+)/*/STORE SOURCE*/;
+  %local rc fref;
+  %let rc= %sysfunc(filename(fref,&file));
+  %if %sysfunc(fdelete(&fref)) ne 0 %then %put %sysfunc(sysmsg());
+  %let rc= %sysfunc(filename(fref));
+%mend mf_deletefile;