get process_create working and add tests

tests/scryer/cli/unix/process.md

@@ -0,0 +1,4 @@
+```trycmd
+$ scryer-prolog -f --no-add-history -g 'use_module(library(process)), process_create("false", [], [process(P)]), process_wait(P, exit(1)), halt'
+
+```

tests/scryer/cli/windows/process.md

@@ -0,0 +1,4 @@
+```trycmd
+$ scryer-prolog -f --no-add-history -g 'use_module(library(process)), process_create("cmd", ["/C", "exit", "1"], [process(P)]), process_wait(P, exit(1)), halt'
+
+```

tests/scryer/main.rs

@@ -19,9 +19,19 @@ mod src_tests;
     ignore = "miri isolation, unsupported operation: can't call foreign function"
 )]
 fn cli_tests() {
-    trycmd::TestCases::new()
+    let cases = trycmd::TestCases::new();
+    cases
         .default_bin_name("scryer-prolog")
         .case("tests/scryer/cli/issues/*.toml")
-        .case("tests/scryer/cli/src_tests/*.toml")
-        .case("tests/scryer/cli/src_tests/*.md");
+        .case("tests/scryer/cli/src_tests/*.toml");
+
+    #[cfg(windows)]
+    {
+        cases.case("tests/scryer/cli/windows/*.md");
+    }
+
+    #[cfg(unix)]
+    {
+        cases.case("tests/scryer/cli/unix/*.md");
+    }
 }